# kb

id: christian-boyling-20260505-0
file: data/en.wikipedia.org/wiki/Christian_Boyling-0.md
category: reference
title: Christian Boyling
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Christian_Boyling
date_saved: 2026-05-05T09:35:48.883715+00:00
instance: kb-cron
parent: christian-boyling-20260505-0
summary:
Christian Boyling (flourished in 1669) was a scientific instrument maker. All that is known for certain about this craftsman is that he was serving as "Mechanic" to the Duke of Saxony in 1669. He designed and built a perpetual calendar held by the Museo Galileo in Florence, consisting of two overlapping brass plates sandwiching a revolving disk containing twelve enameled disks representing the months (eleven are extant) which show through a window on the front plate. The finely perforated front plate is decorated with the arms of the House of Saxony. At its center is a circle showing the hours and containing three-time disks: a moon phase night clock, a perpetual calendar, and a zodiacal calendar showing lengths of the diurnal cycle over the year. == See also == Duke of Saxony == References == == External links ==


id: f-j-duarte-20260505-0
file: data/en.wikipedia.org/wiki/F._J._Duarte-0.md
category: reference
title: F. J. Duarte
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/F._J._Duarte
date_saved: 2026-05-05T09:35:50.108359+00:00
instance: kb-cron
parent: f-j-duarte-20260505-0
summary:
Francisco Javier "Frank" Duarte (born c. 1954) is a laser physicist and author/editor of several books on tunable lasers. His research on physical optics and laser development has won several awards, including an Engineering Excellence Award in 1995 for the invention of the N-slit laser interferometer. == Research == === Laser oscillators === Duarte and Piper introduced multiple-prism near-grazing-incidence grating cavities which originally were disclosed as copper-laser-pumped narrow-linewidth tunable laser oscillators. Subsequently, he developed narrow-linewidth multiple-prism grating configurations for high-power CO2 laser oscillators and solid-state tunable organic laser oscillators. === Intracavity dispersion theory === Duarte also conceived the multiple-prism dispersion theories for tunable narrow-linewidth laser oscillators, and multiple-prism laser pulse compression, which are summarized in several of his books. The introduction to this theory is the generalized multiple-prism dispersion equation ∇ λ ϕ 2 , m = H 2 , m ∇ λ n m + ( k 1 , m k 2 , m ) − 1 ( H 1 , m ∇ λ n m ± ∇ λ ϕ 2 , ( m − 1 ) ) {\displaystyle \nabla _{\lambda }\phi _{2,m}=H_{2,m}\nabla _{\lambda }n_{m}+(k_{1,m}k_{2,m})^{-1}{\bigg (}H_{1,m}\nabla _{\lambda }n_{m}\pm \nabla _{\lambda }\phi _{2,(m-1)}{\bigg )}} which has found a variety of


id: f-j-duarte-20260505-1
file: data/en.wikipedia.org/wiki/F._J._Duarte-1.md
category: reference
title: F. J. Duarte
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/F._J._Duarte
date_saved: 2026-05-05T09:35:50.108359+00:00
instance: kb-cron
parent: f-j-duarte-20260505-0
summary:
=== American phase === In 1983, Duarte traveled to the United States to assume a physics professorship at the University of Alabama. In 1985 he joined the Imaging Research Laboratories, at the Eastman Kodak Company, where he remained until 2006. While at Kodak he was chairman of Lasers '87 and subsequent conferences in this series. Duarte has had a long association with the US Army Missile Command and the US Army Aviation and Missile Command, where he has participated (with R. W. Conrad and T. S. Taylor) in directed energy research. He was elected Fellow of the Australian Institute of Physics in 1987) and a Fellow of the Optical Society of America in 1993. In 1995, he received the Engineering Excellence Award for "the invention of an electrooptic coherent interferometer for direct applications to imaging diagnostics of transparent surfaces, such as photographic film and film substrates. and in 2016, he was awarded the David Richardson Medal for "seminal contributions to the physics and technology of multiple-prism arrays for narrow-linewidth tunable laser oscillators and laser pulse compression," from the Optical Society. === Personal === Duarte was born in Santiago, Chile, and traveled to Sydney, Australia, as a teenager. There, he lived


id: johann-michael-ekling-20260505-0
file: data/en.wikipedia.org/wiki/Johann_Michael_Ekling-0.md
category: reference
title: Johann Michael Ekling
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Johann_Michael_Ekling
date_saved: 2026-05-05T09:35:51.261055+00:00
instance: kb-cron
parent: johann-michael-ekling-20260505-0
summary:
Johann Michael Ekling (also spelt Eckling) (8 August 1795, Vienna – 30 March 1876, Vienna) was an Austrian mechanic and inventor of scientific apparatuses and instruments. == Life == Johann Michael Ekling was the posthumous son of the army surgeon Joseph Ekling. His mother was Anna Maria Euphrosina Ekling née Spitzbarth. He was born in the suburb of Wieden (then a part of Vienna). At the age of 32 he married Theresia Schwarz, with whom he had five sons and a daughter. In the years to follow, he cooperated closely with mathematics and physics professors Andreas von Baumgartner (German Wikipedia) and Andreas von Ettingshausen of the University of Vienna. He produced artificial magnets on behalf of Baumgartner and one of the first photographic apparatuses in Austria (1839) following instructions by Ettingshausen, who had worked with Daguerre. By 1844 he is referred to as a "university mechanic". An announcement in a paper describes his range of products as follows: "[Ekling] makes all sorts of mathematical and physical instruments and apparatuses, air pumps with glass barrel chambers, travel barometers, goniometers, chemical and mineralogical apparatuses". His multiplicator was used for the analysis of mineral waters among other things and praised for its sensitivity.


id: carl-gunnar-engstr-m-20260505-0
file: data/en.wikipedia.org/wiki/Carl_Gunnar_Engström-0.md
category: reference
title: Carl Gunnar Engström
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carl_Gunnar_Engström
date_saved: 2026-05-05T09:35:52.416806+00:00
instance: kb-cron
parent: carl-gunnar-engstr-m-20260505-0
summary:
Carl Gunnar David Engström (1 September 1912 – 9 January 1987) was a Swedish physician and innovator. He is the inventor of the first intermittent positive pressure mechanical ventilator that could deliver breaths of controllable volume and frequency and also deliver inhalation anesthetics. The Engström150 Respirator (EngströmUniversal Respirator) began series production in 1954. The basic principle of the mechanical ventilator is still the same today, but a technological leap was made with the Siemens-Elema servo fan in the 1970s. == Life == Engström was born on 1 September 1912 in Oskarshamn to Carl Johan Engström and Judith Ringberg. He obtained is degree in medicine in 1941. He worked from 1941 at Stockholm Hospital for Infectious Diseases and started to work in the Swedish Air Force in 1956. He got his PhD in medicine at Uppsala University in 1963 with a thesis entitled The clinical application of prolonged controlled ventilation: with special reference to a method developed by the author. Before the invention of Engström, the only available respirator was the iron lung. It is a negative pressure ventilator, a mechanical respirator which encloses most of a person's body, and varies the air pressure in the enclosed space, to stimulate breathing.


id: gualterus-arsenius-20260505-0
file: data/en.wikipedia.org/wiki/Gualterus_Arsenius-0.md
category: reference
title: Gualterus Arsenius
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gualterus_Arsenius
date_saved: 2026-05-05T09:35:53.579060+00:00
instance: kb-cron
parent: gualterus-arsenius-20260505-0
summary:
Gualterus Arsenius (c. 1530 – c. 1580), also known as Gualterius Arsenius, Gautier Arsens, and Walter Arsenius, was a Flemish scientific instrument maker. He was the nephew of the mathematician and cosmographer Gemma Frisius (1508–1555), and he worked in Louvain from 1555 to about 1570 (his presence there is still documented in 1579). The most prominent member of a family of scientific instrument makers, Arsenius produced exquisitely crafted and highly accurate devices such as armillary spheres, astrolabes, astronomical annuli (rings) and sundials, whose designs reveal the influence of his uncle and Gerard Mercator (1512–1594). == References == == External links == "Museo Galileo - object description".


id: pierre-louis-guinand-20260505-0
file: data/en.wikipedia.org/wiki/Pierre-Louis_Guinand-0.md
category: reference
title: Pierre-Louis Guinand
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pierre-Louis_Guinand
date_saved: 2026-05-05T09:35:55.695857+00:00
instance: kb-cron
parent: pierre-louis-guinand-20260505-0
summary:
Pierre-Louis Guinand (1748–1824) was a Swiss lens maker. who in the late 1700s came up with a breakthrough for making better quality and larger glass, and in time went on to teach a young Fraunhofer at Joseph von Utzschneider's (1763-1840) glassworks, and eventually started his own optical glass works. Guinand would supply glass for the Paris Observatory telescopes and also Cauchoix. He was a pioneer in the manufacture of optical glass for microscopes, telescopes, glasses and other optical instruments. == See also == Markree Observatory#Pierre-Louis Guinand == References == == Bibliography == King, Henry C. (1979). The History of the Telescope. New York, NY: Dover Publications, Inc. pp. 176–9, 188–9, 191–2, 196, 204, 252. ISBN 978-0-486-23893-7.


id: johannes-hevelius-20260505-0
file: data/en.wikipedia.org/wiki/Johannes_Hevelius-0.md
category: reference
title: Johannes Hevelius
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Johannes_Hevelius
date_saved: 2026-05-05T09:35:56.877752+00:00
instance: kb-cron
parent: johannes-hevelius-20260505-0
summary:
Johannes Hevelius (in German also known as Hevel; Polish: Jan Heweliusz; (1611-01-28)28 January 1611 – 28 January 1687) was a councillor and chairman of the city council of the Old Town, Gdańsk (in the Polish–Lithuanian Commonwealth). As an astronomer, he gained a reputation as "the founder of lunar topography", and described ten new constellations, seven of which are still used by astronomers. == Etymology == According to the Polish Academy of Sciences (1975) the origin of the name goes back to the surname Hawke, a historical alternative spelling for the English word hawk, which changed into Hawelke or Hawelecke. In Poland he is known as Jan Heweliusz. Other versions of the name include Hewel, Hevel, Hevelke or Hoefel, Höwelcke, Höfelcke. According to Feliks Bentkowski (1814), during his early years he also signed as Hoefelius. Along with the Latinized version of his name, Ludwig Günther-Fürstenwalde (1903) also reports Hevelius's signature as Johannes Höffelius Dantiscanus in 1631 and Hans Höwelcke in 1639. == Early life == Hevelius's father was Abraham Hewelke (1576–1649), his mother Kordula Hecker (1576–1655). They were German-speaking Lutherans, wealthy brewing merchants of Bohemian origin. As a young boy, Hevelius was sent to Gądecz (Gondecz) where he studied the Polish


id: johannes-hevelius-20260505-1
file: data/en.wikipedia.org/wiki/Johannes_Hevelius-1.md
category: reference
title: Johannes Hevelius
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Johannes_Hevelius
date_saved: 2026-05-05T09:35:56.877752+00:00
instance: kb-cron
parent: johannes-hevelius-20260505-0
summary:
In late 1683, in commemoration of the victory of Christian forces led by Polish King John III Sobieski at the Battle of Vienna, he invented and named the constellation Scutum Sobiescianum (Sobieski's Shield), now called Scutum. This constellation first occurred publicly in his star atlas Firmamentum Sobiescianum, which was printed in his own house at lavish expense, and he himself engraved many of the printing plates. His health had suffered from the shock of the 1679 fire and he died on his 76th birthday, 28 January 1687. Hevelius was buried in St. Catherine's Church in his hometown. Descendants of Hevelius live in Urzędów in Poland where they support local astronomy enthusiasts. == Works == Selenographia (1647) De nativa Saturni facie ejusque varis Phasibus (1656) Historiola Mirae (1662), in which he named the periodic variable star Omicron Ceti "Mira", or "the Wonderful" Mercurius in Sole visus Gedani (1662), principally on the transit of Mercury, but containing chapters on many other observations Prodromus cometicus (1665) Cometographia (1668) Machina coelestis (first part, 1673), containing a description of his instruments; the second part (1679) is extremely rare, nearly the whole issue having perished in the conflagration of 1679. Hevelius's description of his "naked eye"


id: hipparchus-20260505-0
file: data/en.wikipedia.org/wiki/Hipparchus-0.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
Hipparchus (; Greek: Ἵππαρχος, Hípparkhos; c. 190 – c. 120 BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hipparchus was born in Nicaea, Bithynia, and probably died on the island of Rhodes, Greece. He is known to have been a working astronomer between 162 and 127 BC. Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and by Meton of Athens (fifth century BC), Timocharis, Aristyllus, Aristarchus of Samos, and Eratosthenes, among others. He developed trigonometry and constructed trigonometric tables, and he solved several problems of spherical trigonometry. His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first known comprehensive star catalog from the western world, and possibly the invention of the astrolabe, as well as of the armillary sphere that he may have used in


id: hipparchus-20260505-1
file: data/en.wikipedia.org/wiki/Hipparchus-1.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
== Geometry, trigonometry and other mathematical techniques == Hipparchus was recognized as the first mathematician known to have possessed a trigonometric table, which he needed when computing the eccentricity of the orbits of the Moon and Sun. He tabulated values for the chord function, which for a central angle in a circle gives the length of the straight line segment between the points where the angle intersects the circle. He may have computed this for a circle with a circumference of 21,600 units and a radius (rounded) of 3,438 units; this circle has a unit length for each arcminute along its perimeter. (This was “proven” by Toomer, but he later “cast doubt“ upon his earlier affirmation. Other authors have argued that a circle of radius 3,600 units may instead have been used by Hipparchus.) He tabulated the chords for angles with increments of 7.5°. In modern terms, the chord subtended by a central angle in a circle of given radius R equals R times twice the sine of half of the angle, i.e.: chord ⁡ θ = 2 R ⋅ sin ⁡ 1 2 θ {\displaystyle \operatorname {chord} \theta =2R\cdot \sin {\tfrac {1}{2}}\theta } The now-lost work in which Hipparchus


id: hipparchus-20260505-2
file: data/en.wikipedia.org/wiki/Hipparchus-2.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
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parent: hipparchus-20260505-0
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=== Orbit of the Moon === It had been known for a long time that the motion of the Moon is not uniform: its speed varies. This is called its anomaly and it repeats with its own period; the anomalistic month. The Chaldeans took account of this arithmetically, and used a table giving the daily motion of the Moon according to the date within a long period. However, the Greeks preferred to think in geometrical models of the sky. At the end of the third century BC, Apollonius of Perga had proposed two models for lunar and planetary motion: In the first, the Moon would move uniformly along a circle, but the Earth would be eccentric, i.e., at some distance of the center of the circle. So the apparent angular speed of the Moon (and its distance) would vary. The Moon would move uniformly (with some mean motion in anomaly) on a secondary circular orbit, called an epicycle that would move uniformly (with some mean motion in longitude) over the main circular orbit around the Earth, called deferent; see deferent and epicycle. Apollonius demonstrated that these two models were in fact mathematically equivalent. However, all this was theory and had


id: hipparchus-20260505-3
file: data/en.wikipedia.org/wiki/Hipparchus-3.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
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parent: hipparchus-20260505-0
summary:
Before Hipparchus, Meton, Euctemon, and their pupils at Athens had made a solstice observation (i.e., timed the moment of the summer solstice) on 27 June 432 BC (proleptic Julian calendar). Aristarchus of Samos is said to have done so in 280 BC, and Hipparchus also had an observation by Archimedes. He observed the summer solstices in 146 and 135 BC both accurately to a few hours, but observations of the moment of equinox were simpler, and he made twenty during his lifetime. Ptolemy gives an extensive discussion of Hipparchus's work on the length of the year in the Almagest III.1, and quotes many observations that Hipparchus made or used, spanning 162–128 BC, including an equinox timing by Hipparchus (at 24 March 146 BC at dawn) that differs by 5 hours from the observation made on Alexandria's large public equatorial ring that same day (at 1 hour before noon). Ptolemy claims his solar observations were on a transit instrument set in the meridian. At the end of his career, Hipparchus wrote a book entitled Peri eniausíou megéthous ("On the Length of the Year") regarding his results. The established value for the tropical year, introduced by Callippus in or before 330 BC


id: hipparchus-20260505-4
file: data/en.wikipedia.org/wiki/Hipparchus-4.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
Hipparchus also undertook to find the distances and sizes of the Sun and the Moon, in the now-lost work On Sizes and Distances (Ancient Greek: Περὶ μεγεθῶν καὶ ἀποστημάτων Peri megethon kai apostematon). His work is mentioned in Ptolemy's Almagest V.11, and in a commentary thereon by Pappus; Theon of Smyrna (2nd century) also mentions the work, under the title On Sizes and Distances of the Sun and Moon. Hipparchus measured the apparent diameters of the Sun and Moon with his diopter. Like others before and after him, he found that the Moon's size varies as it moves on its (eccentric) orbit, but he found no perceptible variation in the apparent diameter of the Sun. He found that at the mean distance of the Moon, the Sun and Moon had the same apparent diameter; at that distance, the Moon's diameter fits 650 times into the circle, i.e., the mean apparent diameters are 360⁄650 = 0°33′14″. Like others before and after him, he also noticed that the Moon has a noticeable parallax, i.e., that it appears displaced from its calculated position (compared to the Sun or stars), and the difference is greater when closer to the horizon. He knew that this


id: hipparchus-20260505-5
file: data/en.wikipedia.org/wiki/Hipparchus-5.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
=== Eclipses === Pliny (Naturalis Historia II.X) tells us that Hipparchus demonstrated that lunar eclipses can occur five months apart, and solar eclipses seven months (instead of the usual six months); and the Sun can be hidden twice in thirty days, but as seen by different nations. Ptolemy discussed this a century later at length in Almagest VI.6. The geometry, and the limits of the positions of Sun and Moon when a solar or lunar eclipse is possible, are explained in Almagest VI.5. Hipparchus apparently made similar calculations. The result that two solar eclipses can occur one month apart is important, because this can not be based on observations: one is visible on the Northern Hemisphere and the other on the Southern Hemisphere—as Pliny indicates—and the latter was inaccessible to the Greek. Prediction of a solar eclipse, i.e., exactly when and where it will be visible, requires a solid lunar theory and proper treatment of the lunar parallax. Hipparchus must have been the first to be able to do this. A rigorous treatment requires spherical trigonometry, thus those who remain certain that Hipparchus lacked it must speculate that he may have made do with planar approximations. He may have discussed


id: hipparchus-20260505-6
file: data/en.wikipedia.org/wiki/Hipparchus-6.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
Hipparchus also constructed a celestial globe depicting the constellations, based on his observations. His interest in the fixed stars may have been inspired by the observation of a supernova (according to Pliny), or by his discovery of precession, according to Ptolemy, who says that Hipparchus could not reconcile his data with earlier observations made by Timocharis and Aristillus. For more information see Discovery of precession. In Raphael's painting The School of Athens, Hipparchus may be depicted holding his celestial globe, as the representative figure for astronomy. It is not certain that the figure is meant to represent him. Previously, Eudoxus of Cnidus in the fourth century BC had described the stars and constellations in two books called Phaenomena and Entropon. Aratus wrote a poem called Phaenomena or Arateia based on Eudoxus's work. Hipparchus wrote a commentary on the Arateia—his only preserved work—which contains many stellar positions and times for rising, culmination, and setting of the constellations, and these are likely to have been based on his own measurements. According to Roman sources, Hipparchus made his measurements with a scientific instrument and he obtained the positions of roughly 850 stars. Pliny the Elder writes in book II, 24–26 of his Natural


id: hipparchus-20260505-7
file: data/en.wikipedia.org/wiki/Hipparchus-7.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
Delambre in his Histoire de l'Astronomie Ancienne (1817) concluded that Hipparchus knew and used the equatorial coordinate system, a conclusion challenged by Otto Neugebauer in his History of Ancient Mathematical Astronomy (1975). Hipparchus seems to have used a mix of ecliptic coordinates and equatorial coordinates: in his commentary on Eudoxus he provides stars' polar distance (equivalent to the declination in the equatorial system), right ascension (equatorial), longitude (ecliptic), polar longitude (hybrid), but not celestial latitude. This opinion was confirmed by the careful investigation of Hoffmann who independently studied the material, potential sources, techniques and results of Hipparchus and reconstructed his celestial globe and its making. As with most of his work, Hipparchus's star catalog was adopted and perhaps expanded by Ptolemy, who has (since Brahe in 1598) been accused by some of fraud for stating (Syntaxis, book 7, chapter 4) that he observed all 1025 stars—critics claim that, for almost every star, he used Hipparchus's data and precessed it to his own epoch 2+2⁄3 centuries later by adding 2°40′ to the longitude, using an erroneously small precession constant of 1° per century. This claim is highly exaggerated because it applies modern standards of citation to an ancient author. True is


id: hipparchus-20260505-8
file: data/en.wikipedia.org/wiki/Hipparchus-8.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
== Geography == Hipparchus's treatise Against the Geography of Eratosthenes in three books is not preserved. Most of our knowledge of it comes from Strabo, according to whom Hipparchus thoroughly and often unfairly criticized Eratosthenes, mainly for internal contradictions and inaccuracy in determining positions of geographical localities. Hipparchus insists that a geographic map must be based only on astronomical measurements of latitudes and longitudes and triangulation for finding unknown distances. In geographic theory and methods Hipparchus introduced three main innovations. He was the first to use the grade grid, to determine geographic latitude from star observations, and not only from the Sun's altitude, a method known long before him, and to suggest that geographic longitude could be determined by means of simultaneous observations of lunar eclipses in distant places. In the practical part of his work, the so-called "table of climata", Hipparchus listed latitudes for several tens of localities. In particular, he improved Eratosthenes's values for the latitudes of Athens, Sicily, and southern extremity of India. In calculating latitudes of climata (latitudes correlated with the length of the longest solstitial day), Hipparchus used an unexpectedly accurate value for the obliquity of the ecliptic, 23°40′ (the actual value in the second


id: hipparchus-20260505-9
file: data/en.wikipedia.org/wiki/Hipparchus-9.md
category: reference
title: Hipparchus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hipparchus
date_saved: 2026-05-05T09:35:58.068622+00:00
instance: kb-cron
parent: hipparchus-20260505-0
summary:
== References == == Works cited == Berger, Ernst Hugo, ed. (1869). Die geographischen Fragmente des Hipparch [The Geographical Fragments of Hipparchus] (in German). Leipzig: Teubner. OCLC 981902787. Cusinato, Bruna; Vanin, Gabriele, eds. (2022) [2013]. Commentari di Ipparco ai Fenomeni di Arato ed Eudosso [Hipparchus' Commentaries on the Phenomena of Aratus and Eudoxus] (in Italian). Translation by Bruna Cusinato; Introduction and astronomical commentary by Gabriele Vanin (3rd ed.). arXiv:2206.08243. Dicks, D. R., ed. (1960). The Geographical Fragments of Hipparchus. University of London classical studies. London: Athlone Press. OCLC 490381. Hoffmann, Susanne M. (2017). Hipparchs Himmelsglobus: Ein Bindeglied in der babylonisch-griechischen Astrometrie? [Hipparchus' Celestial Globe: A Link in Babylonian-Greek Astrometry?] (in German). Wiesbaden: Springer. doi:10.1007/978-3-658-18683-8. ISBN 978-3-658-18683-8. Jones, Alexander (2001). "Hipparchus". In Murdin, Paul (ed.). Encyclopedia of Astronomy and Astrophysics. Bristol: Institute of Physics Pub. ISBN 978-0-333-75088-9. OCLC 1193410336. Manitius, Karl, ed. (1894). Hipparchou Tōn Aratou kai Eudoxou Phainomenōn exēgēseōs vivlia tria = Hipparchi in Arati et Eudoxi Phaenomena commentariorum libri tres [Hipparchus' Commentaries on the Phenomena of Aratus and Eudoxus in three books] (in Ancient Greek and Latin). Leipzig: Teubner. OCLC 1127047584. Neugebauer, Otto E. (1975). A History of Ancient Mathematical Astronomy. Berlin: Springer. Part 1, Part 2, Part 3.


id: fran-ois-antoine-jecker-20260505-0
file: data/en.wikipedia.org/wiki/François-Antoine_Jecker-0.md
category: reference
title: François-Antoine Jecker
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/François-Antoine_Jecker
date_saved: 2026-05-05T09:35:59.288765+00:00
instance: kb-cron
parent: fran-ois-antoine-jecker-20260505-0
summary:
François-Antoine Jecker (November 14, 1765 – September 30, 1834) was a French scientific-instrument maker. Trained in London under Jesse Ramsden, he established a workshop in Paris that produced astronomical, optical, and measuring instruments. == Life and work == Jecker was born in Hirtzfelden near Colmar, Haut-Rhin, the son of a farmer. His brother Laurenz Jecker (1769–1834) became a needle manufacturer. He apprenticed with a watchmaker in Besançon where two uncles worked as musicians. He went to London in 1786 and trained with Jesse Ramsden and returned to Paris in 1792 where he started a workshop to manufacture astronomical instruments and precision measuring instruments. He was joined by his brothers Gervais and Protais and by 1800 he had nearly 40 employees. == References == == External links == Jecker Museum in Hirtzfelden Drum microscopes made by Jecker


id: abu-mahmud-khujandi-20260505-0
file: data/en.wikipedia.org/wiki/Abu-Mahmud_Khujandi-0.md
category: reference
title: Abu-Mahmud Khujandi
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abu-Mahmud_Khujandi
date_saved: 2026-05-05T09:36:00.430468+00:00
instance: kb-cron
parent: abu-mahmud-khujandi-20260505-0
summary:
Abu Mahmud Hamid ibn al-Khidr al-Khujandi (known as Abu Mahmood Khujandi, al-khujandi or Khujandi, Persian: ابومحمود خجندی, c. 940 – 1000) was a Transoxanian astronomer and mathematician. He was born in Khujand (now part of Tajikistan) and lived in the late 10th century. He helped build an observatory, near the city of Ray (near today's Tehran), in Iran. == Astronomy == Khujandi worked under the patronage of the Buwayhid Amirs at the observatory near Ray, Iran. There he is known to have constructed the first huge mural sextant in 994 AD, intended to determine the Earth's axial tilt ("obliquity of the ecliptic") to high precision. He determined the axial tilt to be 23°32'19" for the year 994 AD. He noted that measurements by earlier astronomers had found higher values (Indians: 24°; Ptolemy 23° 51') and thus discovered that the axial tilt is not constant but is in fact (currently) decreasing. His measurement of the axial tilt was however about 2 minutes too small, probably due to his heavy instrument settling over the course of the observations. == Mathematics == Khujandi stated a special case of Fermat's Last Theorem for n = 3, but his attempted proof of the theorem was


id: lala-bulhomal-lahori-20260505-0
file: data/en.wikipedia.org/wiki/Lala_Bulhomal_Lahori-0.md
category: reference
title: Lala Bulhomal Lahori
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lala_Bulhomal_Lahori
date_saved: 2026-05-05T09:36:01.561097+00:00
instance: kb-cron
parent: lala-bulhomal-lahori-20260505-0
summary:
Lāla Bulhomal (also Balhumal) Lāhorī was an Indian metallurgist and instrument maker from the city of Lahore in modern Pakistan. He was famous for crafting ornate astrolabes and celestial globes made in the tradition of Indo-Persian instruments. The toponymic surname Lāhorī indicates that he came from Lahore, while the prefix Lāla is an honorific indicating social status. His instruments, likely made between 1839 and 1851, were constructed mainly of brass, with inscriptions in Sanskrit, Devanagari, Arabic, and Persian. He is known to have produced at least twenty-eight such instruments. Forty-five instruments produced by Bulhomal and his associates are known to exist in museums and collections around the world; an 1849 astrolabe crafted for Sir Henry Miers Elliot, an officer of the East India Company, is now in the Science Museum, London. Bulhomal's patron was Nihal Singh Ahluwalia, the Raja of Kapurthala (1837–1852), and his apprentices included Ghulām Qādir Kapūrthalī and Ustād Pīr Bakhsh Lāhorī. He may also have been associated with contemporary instrument maker Joshi Dharam Chand. Bulhomal's celestial globes were made both for decorative and instructive uses. The stars and constellations on these globes are labeled based on Arabic and Persian versions from Ptolemaic traditions. These seamless and hollow


id: paul-marmet-20260505-0
file: data/en.wikipedia.org/wiki/Paul_Marmet-0.md
category: reference
title: Paul Marmet
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paul_Marmet
date_saved: 2026-05-05T09:36:02.820714+00:00
instance: kb-cron
parent: paul-marmet-20260505-0
summary:
Paul Marmet, (20 May 1932 – 20 May 2005) was a Canadian physicist, inventor, author, and professor at Laval University in Quebec City, Canada, who served as the President of the Canadian Association of Physicists. Marmet is notable for developing a novel high-resolution electron velocity selector, a scientific instrument which became widely used by scientists around the world. == Inventions == Early in his career, Marmet developed a high-resolution electron selector with his mentor Larkin Kerwin, a scientific instrument for studying ionic electronic states. Along with a mass spectrometer Marmet developed, the novel instrument had an energy resolution superior to then-available instruments and has been used widely by scientists studying electron scattering, which led to the discovery of enhanced vibrational excitation in nitrogen and of Feshbach resonances. == Research == Using the Marmet-Kerwin electron selector, Marmet and his research group discovered atomic and molecular states excited by electron impact but not by photons, such as doubly excited states that disobey spectroscopic selection rules. The group also found negative-ion resonances in which the incident electron temporarily attaches to the target atom or molecule. == Career == After receiving his physics BSc in 1956 and DSc in 1960 from Laval University and


id: nastulus-20260505-0
file: data/en.wikipedia.org/wiki/Nastulus-0.md
category: reference
title: Nastulus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nastulus
date_saved: 2026-05-05T09:36:04.021468+00:00
instance: kb-cron
parent: nastulus-20260505-0
summary:
Muḥammad ibn ʿAbd Allāh Nasṭūlus (Arabic: محمد بن عبد الله نسطولس; known as Nasṭūlus, but also referred to as Basṭūlus) was a 10th-century astronomer. He is known for making one of the oldest surviving astrolabes, dated 927/928, as well as of another partially preserved astrolabe that bears his signature, "Made by Nasṭūlus in the year 315" of hijra (925). Very little is known about Nasṭūlus. His full name, based on a testimony given by a contemporary astronomer, Abu Sa'id al-Sijzi, indicates that he was a Muslim, but some modern historians have suggested that his foreign last name may indicate that he was Greek or Nestorian. == References == == Sources == Dodge, Bayard (1970). The Fihrist of Al-Nadīm: A Tenth-century Survey of Muslim Culture. Columbia University Press. ISBN 978-0-231-02925-4. Rius, Mònica (2007). "Nasṭūlus: Muḥammad ibn ʿAbd Allāh". In Thomas Hockey; et al. (eds.). The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 822–3. ISBN 9780387310220. (PDF version) King, David A. (1999). World Maps for Finding the Direction and Distance of Mecca: Examples of Innovation and Tradition in Islamic Science. Brill Publishers. ISBN 978-90-04-11367-1. == Further reading == Websites "A remarkable mathematical and astronomical brass instrument signed by Nastulus, one of


id: friedrich-adolph-nobert-20260505-0
file: data/en.wikipedia.org/wiki/Friedrich_Adolph_Nobert-0.md
category: reference
title: Friedrich Adolph Nobert
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Friedrich_Adolph_Nobert
date_saved: 2026-05-05T09:36:05.169864+00:00
instance: kb-cron
parent: friedrich-adolph-nobert-20260505-0
summary:
Friedrich Adolph Nobert (17 January 1806 – 21 February 1881) was a Pomeranian microscope designer who pioneered the use of diamond-ruled microscope slide gratings for accurate measurements. This extended further to diffraction gratings for use in spectrometers and the measurement of the solar spectrum by Anders Jonas Ångström which was published in 1868 made use of gratings made by Nobert. The finest lines were found to be at a distance of 0.1128 μm. == Biography == Nobert was born in Barth on the Baltic coast, where his father Johann Friedrich Nobert was a clockmaker. He was known as Fritz, and being the eldest son, he was expected to receive a technical education and continue as a clockmaker. A younger brother studied theology and became a pastor. He found his schooling insufficient for the clockmaking work and tried to study arithmetic, geometry and trigonometry on his own. He made a watch that could measure seconds, and corrected for temperature and sent it for an exhibition in Berlin in 1827. This was examined by astronomer Johann Franz Encke who wrote to Nobert and encouraged him to check its accuracy with astronomical measurements. This required a telescope and not able to purchase one,


id: pedro-nunes-20260505-0
file: data/en.wikipedia.org/wiki/Pedro_Nunes-0.md
category: reference
title: Pedro Nunes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pedro_Nunes
date_saved: 2026-05-05T09:36:06.341524+00:00
instance: kb-cron
parent: pedro-nunes-20260505-0
summary:
Pedro Nunes (Portuguese: [ˈpeðɾu ˈnunɨʃ]; Latin: Petrus Nonius; 1502 – 11 August 1578) was a Portuguese mathematician, cosmographer, and professor, probably from a New Christian (of Jewish origin) family. Considered one of the greatest mathematicians of his time, Nunes is best known for being the first to approach navigation and cartography with mathematical tools. Among other accomplishments, he was the first to propose the idea of a loxodrome (a rhumb line), and was the inventor of several measuring devices, including the nonius (from which the Vernier scale was derived), named after his Latin surname. == Life == Little is known about Nunes' early education, life or family background, only that he was born in Alcácer do Sal in Portugal, his origins are possibly Jewish and that his grandchildren spent a few years behind bars after they were accused by the Portuguese Inquisition of professing and secretly practicing Judaism. He studied at the University of Salamanca, maybe from 1517 until 1522. He returned to Lisbon c. 1529 and started teaching at the university. He continued his medical studies but held various teaching posts within the University of Lisbon, including Moral, Philosophy, Logic and Metaphysics. He obtained his doctorate in medicine in


id: pedro-nunes-20260505-1
file: data/en.wikipedia.org/wiki/Pedro_Nunes-1.md
category: reference
title: Pedro Nunes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pedro_Nunes
date_saved: 2026-05-05T09:36:06.341524+00:00
instance: kb-cron
parent: pedro-nunes-20260505-0
summary:
Nunes worked on several practical nautical problems concerning course correction as well as attempting to develop more accurate devices to determine a ship's position. He created the nonius to improve the accuracy of instruments (such as the quadrant). This device consisted of a number of concentric circles traced on the instrument, with each successive circle divided into one fewer division than the adjacent outer circle.Thus, the outermost quadrant would comprise 90° divided into 90 equal parts; the next inner quadrant would have 89 divisions, the next 88, and so on. When an angle was measured, the circle and the division on which the alidade fell was noted. A table was then consulted to provide the exact measure. The nonius was used by Tycho Brahe, who considered it too complex. The method inspired improved systems by Christopher Clavius and Jacob Curtius. These were eventually improved further by Pierre Vernier in 1631, which reduced the nonius to the Vernier scale that includes two scales, one of them fixed and the other movable. Vernier himself used to say that his invention was a perfected nonius and for a long time it was known as the “nonius”, even in France. In some languages, the


id: list-of-developers-of-optical-scientific-equipment-20260505-0
file: data/en.wikipedia.org/wiki/List_of_developers_of_optical_scientific_equipment-0.md
category: reference
title: List of developers of optical scientific equipment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_developers_of_optical_scientific_equipment
date_saved: 2026-05-05T09:36:07.567295+00:00
instance: kb-cron
parent: list-of-developers-of-optical-scientific-equipment-20260505-0
summary:
A developer of optical scientific equipment is an individual who makes and adjusts optical aids for scientific purposes, including telescope optics and microscope lenses. == Telescope developers == James Gilbert Baker Denis Albert Bardou John A. Brashear Laurent Cassegrain Henri Chrétien Alvan Clark John Dollond Charles Wesley Elmer and Richard Scott Perkin Galileo Galilei James Gregory John Hadley Chester Moore Hall Robert Hooke Johannes Kepler Frederick James Hargreaves Christiaan Huygens Hans Lippershey Raymond Augustin Mailhat Dmitri Dmitrievich Maksutov James Henry Marriott Jacob Metius Isaac Newton Georg Simon Plössl Russell W. Porter Jesse Ramsden George Willis Ritchey Christoph Scheiner Bernhard Schmidt James Short See also Timeline of telescope technology and List of astronomical instrument makers == Microscope developers == Ernst Karl Abbe Denis Albert Bardou Christopher Cock Siegfried Czapski Cornelius Drebbel Galileo Galilei Robert Hooke Christiaan Huygens Carl Kellner Anton van Leeuwenhoek Moritz von Rohr See also Timeline of microscope technology == References ==


id: simon-pl-ssl-20260505-0
file: data/en.wikipedia.org/wiki/Simon_Plössl-0.md
category: reference
title: Simon Plössl
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Simon_Plössl
date_saved: 2026-05-05T09:36:08.713363+00:00
instance: kb-cron
parent: simon-pl-ssl-20260505-0
summary:
Simon Plössl (September 19, 1794, Vienna – January 29, 1868, Vienna) was an Austrian optical instrument maker. Initially trained at the Voigtländer company, he set up his own workshop in 1823. His major achievement at the time was the improvement of the achromatic microscope objective. Today he is best known for the eponymous Plössl telescope eyepiece, which follows his 1860 design and has been used extensively by amateur astronomers since the 1980s. == External links == Instruments by Simon Georg Plössl 10 Plössl, Georg Simon A short biography and some instruments from the Hellenic Archives of Scientific Instruments Early large microscope by Simon Plössl, made in 1840 Early travel microscope by Simon Plössl, made in 1845 Plössl Non-inclining Large Microscope, c. 1845


id: ivan-puluj-20260505-0
file: data/en.wikipedia.org/wiki/Ivan_Puluj-0.md
category: reference
title: Ivan Puluj
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ivan_Puluj
date_saved: 2026-05-05T09:36:09.885912+00:00
instance: kb-cron
parent: ivan-puluj-20260505-0
summary:
Ivan Pavlovych Puluj (Ukrainian: Іван Павлович Пулюй, pronounced [iˈwɑn pʊˈlʲuj]; German: Johann Puluj; 2 February 1845 – 31 January 1918) was a Ukrainian physicist and inventor known for his early research into X-rays. His contributions were largely neglected until the end of the 20th century. == Biography == Puluj was born on 2 February 1845 in Hrymailiv, which was then part of the Kingdom of Galicia and Lodomeria in the Austrian Empire. He was the son of Pavlo Puluj and Xenia née Burshtynska (Ukrainian: син Павла́ Пулю́я i Ксенiї ур. Бурштинської). The family's original surname was Pulguy until 1861. His father, Pavlo, was a landowner who served as burgomaster of Hrymayliv from 1861 to 1865. Ivan grew up in Hrymayliv, and attended primary school in the village. He then attended the gymnasium at Ternopil, where he became a co-founder and active member of the Ukrainian student society Hromada. He graduated with honors from Theological Faculty of the University of Vienna (1869), later also from the Department of Philosophy (1872). During his time there, he was the co-founder and later head of the Sich movement. After graduating, he worked as an assistant to the University of Vienna's experimental physics department. In


id: radiguet-et-fils-20260505-0
file: data/en.wikipedia.org/wiki/Radiguet_et_Fils-0.md
category: reference
title: Radiguet et Fils
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Radiguet_et_Fils
date_saved: 2026-05-05T09:36:11.718314+00:00
instance: kb-cron
parent: radiguet-et-fils-20260505-0
summary:
Radiguet et Fils (stylized Radiguet & Fils; English: "Radiguet and Son") was a French manufacturer of precision scientific instruments, established in 1805. According to a history of the firm published in L'Industrie parisienne in 1888, the company was founded in 1805 by a Madame Collot. Ownership then passed to Louis Chevalier (c.1778-1848), younger brother of Vincent Chevalier. In 1830, Chevalier left the company to Honoré-Marie Radiguet (1791-1867), who had once worked as Chevalier's apprentice, and who had made a name for himself in the production of optical equipment, especially parallel mirrors [glaces parallèles] for astronomy and maritime navigation. Under the management of Honoré-Marie's son, Antoine-Honoré Radiguet (1824-1887), the company's purview expanded to include barometers, thermometers, and other scientific equipment. Antoine-Honoré was president of the Trade Association of Precision Instruments [chambre syndicale des instruments de précision]. Antoine-Honoré's financial investment in the application of parallel mirrors to daguerreotype photography lost the company significant sums, as the problem of image reversal which the introduction of his mirrors was supposed to solve was solved by other means. Antoine-Honoré and his son Arthur (1850-1905) marketed their company to a broader public through engineering and photography workshops, as well as through a line of scientific toys


id: horace-b-n-dict-de-saussure-20260505-0
file: data/en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure-0.md
category: reference
title: Horace Bénédict de Saussure
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure
date_saved: 2026-05-05T09:36:12.944546+00:00
instance: kb-cron
parent: horace-b-n-dict-de-saussure-20260505-0
summary:
Horace Bénédict de Saussure (French: [ɔʁas benedikt də sosyʁ]; 17 February 1740 – 22 January 1799) was a Genevan geologist, meteorologist, physicist, mountaineer and Alpine explorer (specifically the Mont Blanc massif), often called the founder of alpinism and modern meteorology, and considered to be the first person to build a successful solar oven. == Early life and education == Horace Bénédict de Saussure was born 17 February 1740, in Conches, near Geneva, in the Republic of Geneva. Saussure's family were Genevan patricians. His father, Nicolas de Saussure, was an agriculturist, agronomist and author. Because his mother was "sickly", Saussure was brought up by his mother's sister and her husband the Genevan naturalist Charles Bonnet, who sparked Horace-Bénédict's early interest in botany. After attending the "Collège" of his hometown, he completed his studies at the Geneva Academy in 1759 with a dissertation on heat (Dissertatio physica de igne). == Career == In 1760, Saussure made the first of numerous trips to Chamonix valley, to collect plant specimens for the noted Swiss anatomist, physiologist and botanist Albrecht von Haller. In 1760, Saussure offered a reward to the first man to reach the summit of Mont Blanc. Inspired by his uncle, Charles Bonnet,


id: horace-b-n-dict-de-saussure-20260505-1
file: data/en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure-1.md
category: reference
title: Horace Bénédict de Saussure
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure
date_saved: 2026-05-05T09:36:12.944546+00:00
instance: kb-cron
parent: horace-b-n-dict-de-saussure-20260505-0
summary:
All of Saussure's observations and experiments from seven Alpine journeys were summed up and published in four quarto volumes, under the general title of Voyages dans les Alpes (1779 – 1796) (There was an octavo issue in eight volumes, issued from 1780 to 1796). The non-scientific portions of the work were first published in 1834, and often since, as Partie pittoresque des ouvrages de M. de Saussure. The Alps were the focus of Saussure's investigations. He saw them as the grand key to the true theory of the earth, and they gave him the opportunity to study geology in a manner never previously attempted. Saussure closely examined the inclination of the strata, the nature of the rocks, the fossils and the minerals. Saussure had a thorough knowledge of the chemistry of the day and applied it to the study of minerals, water and air. His geological observations made him a firm believer in the Neptunian theory: He regarded all rocks and minerals as deposited from aqueous solution or suspension, and attached much importance to the study of meteorological conditions. His work with rocks, erosion, and fossils also led him to believe that the earth was much older than generally thought


id: horace-b-n-dict-de-saussure-20260505-2
file: data/en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure-2.md
category: reference
title: Horace Bénédict de Saussure
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Horace_Bénédict_de_Saussure
date_saved: 2026-05-05T09:36:12.944546+00:00
instance: kb-cron
parent: horace-b-n-dict-de-saussure-20260505-0
summary:
== References == Lives by J Senebier (Geneva, 1801), by Cuvier in the Biographie universelle, and by A. P. de Candolle in Décade philosophique DeCandolle, A.P. (1799). "XVII. Biographical memoirs of M. de Saussure". Philosophical Magazine. Series 1. 4 (13): 96–102. doi:10.1080/14786449908677038. articles by E. Naville in the Bibliothèque universelle (March, April, May 1883) chaps. v.-viii. of Ch. Durier's Le Mont-Blanc (Paris, various editions between 1877 and 1897). This article incorporates text from a publication now in the public domain: Coolidge, William Augustus Brevoort (1911). "Saussure, Horace Bénédict de". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 24 (11th ed.). Cambridge University Press. p. 238. René Sigrist, Le capteur solaire de Horace-Bénédict de Saussure. Genèse d'une science empirique. Geneva, Passé-Présent / Jullien, 1993. Albert V. Carozzi & Gerda Bouvier, The scientific library of Horace-Bénédict de Saussure (1797): annotated catalog of an 18th-century bibliographic and historic treasure, Geneva, 1994 (Mémoires de la SPHN, t. 46). René Sigrist (ed.), H.-B. de Saussure (1740–1799): un regard sur la terre. Geneva, Georg, 2001. == External links == Pictures and texts of "Les Voyages dans les Alpes" by H. B. de Saussure can be found in the database VIATIMAGES (archived from www3.unil.ch) Horace-Benedict de Saussure and


id: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-0
file: data/en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf-0.md
category: reference
title: Taqi ad-Din Muhammad ibn Ma'ruf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf
date_saved: 2026-05-05T09:36:14.178868+00:00
instance: kb-cron
parent: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-0
summary:
Taqi ad-Din Muhammad ibn Ma'ruf ash-Shami al-Asadi (Arabic: تقي الدين محمد بن معروف الشامي; Ottoman Turkish: تقي الدين محمد بن معروف الشامي السعدي; Turkish: Takiyüddin‎ 1526–1585) was an Ottoman polymath active in Cairo and Istanbul. He was the author of more than ninety books on a wide variety of subjects, including astronomy, clocks, engineering, mathematics, mechanics, optics, and natural philosophy. In 1574 the Ottoman Sultan Murad III invited Taqi ad-Din to build an observatory in the Ottoman capital, Istanbul. Taqi ad-Din constructed instruments such as an armillary sphere and mechanical clocks that he used to observe the Great Comet of 1577. He also used European celestial and terrestrial globes that were delivered to Istanbul in gift exchanges. His major work from the use of his observatory is titled "The tree of ultimate knowledge [in the end of time or the world] in the Kingdom of the Revolving Spheres: The astronomical tables of the King of Kings [Murad III]" (Sidrat al-muntah al-afkar fi malkūt al-falak al-dawār– al-zij al-Shāhinshāhi). The work was prepared according to the results of the observations carried out in Egypt and Istanbul in order to correct and complete Ulugh Beg's 15th century work, the Zij-i Sultani. The first


id: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-1
file: data/en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf-1.md
category: reference
title: Taqi ad-Din Muhammad ibn Ma'ruf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf
date_saved: 2026-05-05T09:36:14.178868+00:00
instance: kb-cron
parent: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-0
summary:
The main purpose behind the observatory was to cater to the needs of the astronomers and provide a library and workshop so they could design and produce instruments. This observatory would become one of the largest ones in the Islamic world. It was complete in 1579. It would go on to run until January 22, 1580 which is when it was destroyed. Some say religious arguments was the reason why it was destroyed, but it really came down to political problems. A report by the grand vizier Sinan Pasha to Sultan Murad III goes into how the Sultan and the vizier attempted to keep Taqī Ad-Dīn away from the ulama because it seemed like they wanted to take him to trial for heresy. The vizier informs the sultan that Taqī Ad-Dīn wanted to go to Syria regardless of the sultan's orders. The vizier also warned the sultan that if Taqī Ad-Dīn went there, there is a possibility that he would be noticed by the ulama who would take him to trial. Despite Taqī al-Dīn's originality, his influence seemed to be limited. There are only a small number of surviving copies of his works so they were not able to reach


id: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-2
file: data/en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf-2.md
category: reference
title: Taqi ad-Din Muhammad ibn Ma'ruf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf
date_saved: 2026-05-05T09:36:14.178868+00:00
instance: kb-cron
parent: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-0
summary:
=== Politics === The rise and fall of Taqī al-Dīn and his observatory depended on political issues that surrounded him. Due to his father's occupation as a professor at the Damascene College of law Taqī al-Dīn spent much of his life in Syria and Egypt. During his trips to Istanbul he was able to make connections with many scholar-jurists. He was also able to use the private library of the Grand Vizier of the time, Semiz Ali Pasha. He then began working under Sultan Murad III's new Grand Vizier's, private mentor Sokollu. Continuing his research on observations of the heavens while in Egypt Taqī al-Dīn used the Galata tower and Sokollu's private residence. Although Murad III was the one who commanded an observatory to be built it was actually Sokollu who brought the idea to him knowing about his interest in science. The Sultan ultimately would provide Taqī al-Dīn with everything he needed from financial assistance for the physical buildings, to intellectual assistance making sure he had easy access to many types of books he would need. When the Sultan decided to create the observatory he saw it as a way to show off the power his monarchy had besides


id: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-3
file: data/en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf-3.md
category: reference
title: Taqi ad-Din Muhammad ibn Ma'ruf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Taqi_ad-Din_Muhammad_ibn_Ma'ruf
date_saved: 2026-05-05T09:36:14.178868+00:00
instance: kb-cron
parent: taqi-ad-din-muhammad-ibn-ma-ruf-20260505-0
summary:
==== Types of clocks examined ==== Of the clocks in the Grand Vizier's treasury Taqī al-Dīn examined three different types. Those three were weight-driven, spring-driven, and driven by lever escapement. He wrote of these three types of watches but also made comments on pocket watches and astronomical ones. As Chief Astronomer, Taqī al-Dīn created a mechanical astronomical clock. This clock was made to permit more precise measurements at the Constantinople observatory. As stated above the creation of this clock was thought to be one of the most important astronomical discoveries of the sixteenth century. Taqī al-Dīn constructed a mechanical clock with three dials which show the hours, minutes, and seconds, with each minute consisting of five seconds. After this clock it is not known whether Taqī al-Dīn's work in mechanical clocks was ever continued, given that much of the clockmaking after that time in the Ottoman Empire was taken over by Europeans. === Steam === In 1551 Taqī al-Dīn described a self-rotating spit that is important in the history of the steam turbine. In Al-Turuq al-samiyya fi al-alat al-ruhaniyya (The Sublime Methods of Spiritual Machines) al-Dīn describes this machine as well as some practical applications for it. The spit is


id: ulugh-beg-20260505-0
file: data/en.wikipedia.org/wiki/Ulugh_Beg-0.md
category: reference
title: Ulugh Beg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ulugh_Beg
date_saved: 2026-05-05T09:36:15.412895+00:00
instance: kb-cron
parent: ulugh-beg-20260505-0
summary:
Mīrzā Muhammad Tarāghāy bin Shāhrukh (Chagatay: میرزا محمد تراغای بن شاهرخ; Persian: میرزا محمد طارق بن شاهرخ), better known as Ulugh Beg (Persian: الغ‌بیک; 22 March 1394 – 27 October 1449), was a Timurid sultan, as well as an astronomer and mathematician. Ulugh Beg was notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry, as well as his general interests in the arts and intellectual activities. It is thought that he spoke five languages: Arabic, Persian, Chaghatai Turkic, Mongolian, and a small amount of Chinese. During his rule (first as a governor, then outright) the Timurid Empire achieved the cultural peak of the Timurid Renaissance through his attention and patronage. Samarkand was captured and given to Ulugh Beg by his father Shah Rukh. He built the great Ulugh Beg Observatory in Samarkand between 1424 and 1429. It was considered by scholars to have been one of the finest observatories in the Islamic world at the time and the largest in Central Asia. Ulugh Beg was subsequently recognized as the most important observational astronomer from the 15th century by many scholars. He also built the Ulugh Beg Madrasah (1417–1420) in Samarkand and Bukhara, transforming the cities into


id: ulugh-beg-20260505-1
file: data/en.wikipedia.org/wiki/Ulugh_Beg-1.md
category: reference
title: Ulugh Beg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ulugh_Beg
date_saved: 2026-05-05T09:36:15.412895+00:00
instance: kb-cron
parent: ulugh-beg-20260505-0
summary:
Astronomy piqued Ulugh Beg's interest when he visited the Maragheh Observatory at a young age. This observatory, located in Maragheh, Iran, is where the well-known astronomer Nasir al-Din al-Tusi practised. In 1428, Ulugh Beg built an enormous observatory, similar to Tycho Brahe's later Uraniborg as well as Taqi al-Din's observatory in Constantinople. Lacking telescopes to work with, he increased his accuracy by increasing the length of his sextant; the so-called Fakhri sextant had a radius of about 36 meters (118 feet) and the optical separability of 180" (seconds of arc). The Fakhri sextant was the largest instrument at the observatory in Samarkand (an image of the sextant is on the side of this article). There were many other astronomical instruments located at the observatory, but the Fakhri sextant is the most well-known instrument there. The purpose of the Fakhri sextant was to measure the transit altitudes of the stars. This was a measurement of the maximum altitude above the horizon of the stars. It was only possible to use this device to measure the declination of celestial objects. The image, which can be found in this article, shows the remaining portion of the instrument, which consists of the underground, lower


id: ulugh-beg-20260505-2
file: data/en.wikipedia.org/wiki/Ulugh_Beg-2.md
category: reference
title: Ulugh Beg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ulugh_Beg
date_saved: 2026-05-05T09:36:15.412895+00:00
instance: kb-cron
parent: ulugh-beg-20260505-0
summary:
Ulugh Beg led two major campaigns against his neighbours. This first one took place in 1425 and was directed against Moghulistan and its ruler Shir Muhammad. He was victorious but the impact of the campaign was limited and Shir Muhammad remained in power. A year later, Baraq, Khan of the Golden Horde and former protégé of Ulugh Beg, laid claim to Timurid possessions around the Syr Darya, including the town of Sighnaq. In response to that, in 1427 Ulugh Beg, accompanied by his brother Muhummad Juki, marched against Baraq. In a hill close to Sighnaq the Timurid army was surprised by a smaller enemy force but was soundly defeated. The humiliation suffered at the hands of Baraq was to have a lasting effect on Ulugh Beg. His campaign against the Golden Horde would be the last he would undertake against a neighbouring power. The armies he later sent against them would not win any resounding victories and by the end of his reign his territories would be raided by his northern and easterly foes. In 1439, the Zhengtong emperor ordered an artist to produce a painting of a black horse with white feet and a white forehead that had been


id: ulugh-beg-20260505-3
file: data/en.wikipedia.org/wiki/Ulugh_Beg-3.md
category: reference
title: Ulugh Beg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ulugh_Beg
date_saved: 2026-05-05T09:36:15.412895+00:00
instance: kb-cron
parent: ulugh-beg-20260505-0
summary:
== Bibliography == O'Connor, John J.; Robertson, Edmund F., "Ulugh Beg", MacTutor History of Mathematics Archive, University of St Andrews 1839. L. P. E. A. Sedillot (1808–1875). Tables astronomiques d’Oloug Beg, commentees et publiees avec le texte en regard, Tome I, 1 fascicule, Paris. A very rare work, but referenced in the Bibliographie generale de l’astronomie jusqu’en 1880, by J. 1847. L. P. E. A. Sedillot (1808–1875). Prolegomenes des Tables astronomiques d’Oloug Beg, publiees avec Notes et Variantes, et precedes d’une Introduction. Paris: F. Didot. 1853. L. P. E. A. Sedillot (1808–1875). Prolegomenes des Tables astronomiques d’Oloug Beg, traduction et commentaire. Paris. Le Prince Savant annexe les étoiles, Frédérique Beaupertuis-Bressand, in Samarcande 1400–1500, La cité-oasis de Tamerlan : coeur d'un Empire et d'une Renaissance, book directed by Vincent Fourniau, éditions Autrement, 1995, ISSN 1157-4488. L'âge d'or de l'astronomie ottomane, Antoine Gautier, in L'Astronomie, (Monthly magazine created by Camille Flammarion in 1882), December 2005, volume 119. L'observatoire du prince Ulugh Beg, Antoine Gautier, in L'Astronomie, (Monthly magazine created by Camille Flammarion in 1882), October 2008, volume 122. Le recueil de calendriers du prince timouride Ulug Beg (1394–1449), Antoine Gautier, in Le Bulletin, n° spécial Les calendriers, Institut National des Langues et


id: pierre-vernier-20260505-0
file: data/en.wikipedia.org/wiki/Pierre_Vernier-0.md
category: reference
title: Pierre Vernier
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pierre_Vernier
date_saved: 2026-05-05T09:36:16.630856+00:00
instance: kb-cron
parent: pierre-vernier-20260505-0
summary:
Pierre Vernier (French pronunciation: [pjɛʁ vɛʁnje]; 19 August 1580 at Ornans, Franche-Comté (at that time ruled by the Spanish Habsburgs, now part of France) – 14 September 1637, same location) was a mathematician and instrument inventor. He was the inventor and eponym of the vernier scale used in measuring devices. == Life == He was born in Ornans, France, in 1580. He was taught science by his father. He became captain and castellan of the castle at Ornans, for the King of Spain. He was also later councillor and director general of economy in the County of Burgundy. In Brussels, in the year 1631, Vernier published his treatise La construction, l'usage, et les propriétés du quadrant nouveau de mathématique, and dedicated it to the Infanta. In it, he described the ingenious device which now bears his name, the vernier scale. To a quadrant with a primary scale in half degrees Vernier proposed to attach a movable sector, thirty-one half degrees in length but divided into thirty equal parts (each part therefore consisting of a half-degree plus one minute). In measuring an angle, minutes could be easily reckoned by noticing which division line of the sector coincided with a division line


id: les-william-20260505-0
file: data/en.wikipedia.org/wiki/Les_William-0.md
category: reference
title: Les William
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Les_William
date_saved: 2026-05-05T09:36:17.760881+00:00
instance: kb-cron
parent: les-william-20260505-0
summary:
J. L. (Les) William (18 January 1915 – 4 June 1994) was an Australian builder of scientific instruments. Born in Melbourne, Australia he was known for his beautiful and precision craftsmanship and was known as one of the best scientific instrument makers in Australia. His equipment can be found in Australian laboratories that existed from the 1930s through to the 1980s. He founded a company situated in the Melbourne suburb of Hughesdale called J.L. William Scientific Instruments. William attended Caulfield Technical School and worked at his brother's firm during the Second World War. Soon after he set up his own instrumentation company. He never married and in his later years suffered from motor neurone disease. Les William liked to recall Lord Kelvin's dictum that one did not truly understand a scientific quantity until one could measure it and provide an accurate numerical value. William's career was closely linked to that of his older brother Austin (1913 - 1985). During the Second World War the two brothers worked together producing electrical meters. After the war, Austin continued on in the manufacture of electrical meters while Les established his own company producing high accuracy standard resistors. He died in Melbourne on 4


id: al-zarqali-20260505-0
file: data/en.wikipedia.org/wiki/Al-Zarqali-0.md
category: reference
title: Al-Zarqali
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Al-Zarqali
date_saved: 2026-05-05T09:36:18.928040+00:00
instance: kb-cron
parent: al-zarqali-20260505-0
summary:
Abū Isḥāq Ibrāhīm ibn Yaḥyā al-Naqqāsh al-Zarqālī al-Tujibi (Arabic: إبراهيم بن يحيى الزرقالي); also known as Al-Zarkali or Ibn Zarqala (1029–1100), was an Arab maker of astronomical instruments and an astrologer from the western part of the Islamic world. Although his name is conventionally given as al-Zarqālī, it is probable that the correct form was al-Zarqālluh. In Latin he was referred to as Arzachel or Arsechieles, a modified form of Arzachel, meaning 'the engraver'. He lived in Toledo, Al-Andalus before moving to Córdoba later in his life. His works inspired a generation of Islamic astronomers in Al-Andalus, and later, after being translated, were very influential in Europe. His invention of the Saphaea (a perfected astrolabe) proved very popular and was widely used by navigators until the 16th century. The crater Arzachel on the Moon is named after him. == Life == Al-Zarqālī, of Arab origin, was born in a village near the outskirts of Toledo, the then capital of the newly established Taifa of Toledo. He started work after 1048 under Said al-Andalusi for the Emir Al-Mamun of Toledo and also under Al-Mu'tamid of the Taifa of Seville. Assuming a leading position under Said, Al-Zarqālī conducted solar observations for 25


id: al-zarqali-20260505-1
file: data/en.wikipedia.org/wiki/Al-Zarqali-1.md
category: reference
title: Al-Zarqali
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Al-Zarqali
date_saved: 2026-05-05T09:36:18.928040+00:00
instance: kb-cron
parent: al-zarqali-20260505-0
summary:
=== Tables of Toledo === Al-Zarqālī also contributed to the famous Tables of Toledo, an adaptation of earlier astronomical data by Al-Khwarizmi and Al-Battani, to locate the coordinates of Toledo. His zij and almanac were translated into Latin by Gerard of Cremona in the 12th century, and contributed to the rebirth of a mathematically based astronomy in Christian Europe and were later incorporated into the Tables of Toledo in the 12th century and the Alfonsine tables in the 13th century. Famous as well for his own Book of Tables, of which many had been compiled. Al-Zarqālī's almanac contained tables which allowed one to find the days on which the Coptic, Roman, lunar, and Persian months begin, other tables which give the position of planets at any given time, and still others facilitating the prediction of solar and lunar eclipses. This almanac that he compiled directly provided "the positions of the celestial bodies and need no further computation", it further simplifies longitudes using planetary cycles of each planet. The work provided the true daily positions of the sun for four Julian years from 1088 to 1092, the true positions of the five planets every 5 or 10 days over a period


id: ballistic-galvanometer-20260505-0
file: data/en.wikipedia.org/wiki/Ballistic_galvanometer-0.md
category: reference
title: Ballistic galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ballistic_galvanometer
date_saved: 2026-05-05T09:36:32.373814+00:00
instance: kb-cron
parent: ballistic-galvanometer-20260505-0
summary:
A ballistic galvanometer is a type of sensitive galvanometer; commonly a mirror galvanometer. Unlike a current-measuring galvanometer, the moving part has a large moment of inertia, thus giving it a long oscillation period. It is really an integrator measuring the quantity of charge discharged through it. It can be either of the moving coil or moving magnet type. Before first use the ballistic constant of the galvanometer must be determined. This is usually done by connecting to the galvanometer a known capacitor, charged to a known voltage, and recording the deflection. The constant K is calculated from the capacitance C, the voltage V and the deflection d: K = C V / d {\displaystyle K=CV/d} where K is expressed in coulombs per centimeter. In operation the unknown quantity of charge Q (in coulombs) is simply: Q = k d {\displaystyle Q=kd} . == Grassot Fluxmeter == The Grassot Fluxmeter solves a particular problem encountered with regular galvanometers. For a regular galvanometer, the discharge time must be shorter than the natural period of oscillation of the mechanism. In some applications, particularly those involving inductors, this condition cannot be met. The Grassot fluxmeter resolves this problem, by operating without any restoring force,


id: bygrave-slide-rule-20260505-0
file: data/en.wikipedia.org/wiki/Bygrave_slide_rule-0.md
category: reference
title: Bygrave slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bygrave_slide_rule
date_saved: 2026-05-05T09:36:34.708068+00:00
instance: kb-cron
parent: bygrave-slide-rule-20260505-0
summary:
The Bygrave slide rule is a slide rule named for its inventor, Captain Leonard Charles Bygrave of the RAF. It was used in celestial navigation, primarily in aviation. Officially, it was called the A. M. L. Position Line Slide Rule (A.M.L. for Air Ministry Laboratories). It was developed in 1920 at the Air Ministry Laboratories at Kensington in London and was produced by Henry Hughes & Son Ltd of London until the mid-1930s. It solved the so-called celestial triangle accurately to about one minute of arc and quickly enough for aerial navigation. The solution of the celestial triangle used the John Napier rules for solution of square-angled spherical triangles. The slide rule was constructed as two coaxial tubes with spiral scales, like the Fuller's cylindrical slide rules, with yet another tube on the outside carrying the cursors. During the Second World War, a closely related version was produced in Germany by Dennert & Pape as the HR1, MHR1 and HR2. == Famous users == Sir Francis Chichester was a renowned aviator and yachtsman. He used a Bygrave Slide Rule as an aid to navigation during flights in the 1930s, one of which was the first solo flight from New Zealand


id: cavallo-s-multiplier-20260505-0
file: data/en.wikipedia.org/wiki/Cavallo's_multiplier-0.md
category: reference
title: Cavallo's multiplier
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cavallo's_multiplier
date_saved: 2026-05-05T09:36:37.078596+00:00
instance: kb-cron
parent: cavallo-s-multiplier-20260505-0
summary:
Cavallo's multiplier was an early electrostatic influence machine, invented in 1795 by the Anglo-Italian natural philosopher Tiberius Cavallo. Its purpose was to multiply, or amplify, a small electric charge to a level where it was detectable by the insensitive electroscopes of the day. Repeated operation of the device could produce voltages high enough to generate sparks. == Description == Cavallo described his machine in his 1795 Treatise on Electricity. He had examined Bennet's charge doubler of 1787 and found it wanting in several regards, notably in its inconsistent operation and tendency to retain the charge from an earlier experiment. Cavallo resolved to build a better device. His machine consisted of four metal plates supported on a wooden board by posts, of which three were insulating and one conducting. The charge to be multiplied was applied to the first of these (plate A), which stood on an insulating post. A moveable insulated metal plate (B) was brought close to A (though not permitted to touch it), and then grounded. The charge on A caused charge separation on B due to electrostatic induction. Plate B was then moved away, breaking its earth connection. Since B was insulated, it acquired and retained a


id: crookes-tube-20260505-0
file: data/en.wikipedia.org/wiki/Crookes_tube-0.md
category: reference
title: Crookes tube
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crookes_tube
date_saved: 2026-05-05T09:36:41.769217+00:00
instance: kb-cron
parent: crookes-tube-20260505-0
summary:
A Crookes tube (also Crookes–Hittorf tube) is an early experimental discharge tube with partial vacuum invented by English physicist William Crookes and others around 1869–1875, in which cathode rays, streams of electrons, were discovered. Developed from the earlier Geissler tube, the Crookes tube consists of a partially evacuated glass bulb of various shapes, with two metal electrodes, the cathode and the anode, one at either end. When a high voltage is applied between the electrodes, cathode rays (electrons) are projected in straight lines from the cathode. It was used by Crookes, Johann Hittorf, Julius Plücker, Eugen Goldstein, Heinrich Hertz, Philipp Lenard, Kristian Birkeland and others to discover the properties of cathode rays, culminating in J. J. Thomson's 1897 identification of cathode rays as negatively charged particles, which were later named electrons. Crookes tubes are now used only for demonstrating cathode rays. Wilhelm Röntgen discovered X-rays using the Crookes tube in 1895. The term Crookes tube is also used for the first generation, cold cathode X-ray tubes, which evolved from the experimental Crookes tubes and were used until about 1920. == History == === Invention === Crookes tubes evolved from the earlier Geissler tubes invented by the German physicist and glassblower


id: crookes-tube-20260505-1
file: data/en.wikipedia.org/wiki/Crookes_tube-1.md
category: reference
title: Crookes tube
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crookes_tube
date_saved: 2026-05-05T09:36:41.769217+00:00
instance: kb-cron
parent: crookes-tube-20260505-0
summary:
=== Discovery of X-rays === When the voltage applied to a Crookes tube is high enough, around 5,000 volts or greater, it can accelerate the electrons to a high enough velocity to create X-rays when they hit the anode or the glass wall of the tube. The fast electrons emit X-rays when their path is bent sharply as they pass near the high electric charge of an atom's nucleus, a process called bremsstrahlung, or they knock an atom's inner electrons into a higher energy level, and these in turn emit X-rays as they return to their former energy level, a process called X-ray fluorescence. Many early Crookes tubes undoubtedly generated X-rays, because early researchers such as Ivan Pulyui had noticed that they could make foggy marks on nearby unexposed photographic plates. On November 8, 1895, Wilhelm Röntgen was operating a Crookes tube covered with black cardboard when he noticed that a nearby fluorescent screen glowed faintly. He realized that some unknown invisible rays from the tube were able to pass through the cardboard and make the screen fluoresce. He found that they could pass through books and papers on his desk. Röntgen began to investigate the rays full-time, and on


id: crookes-tube-20260505-2
file: data/en.wikipedia.org/wiki/Crookes_tube-2.md
category: reference
title: Crookes tube
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crookes_tube
date_saved: 2026-05-05T09:36:41.769217+00:00
instance: kb-cron
parent: crookes-tube-20260505-0
summary:
=== Cathode rays move in parallel lines === Julius Plücker in 1869 built a tube with an anode shaped like a Maltese Cross facing the cathode. It was hinged, so it could fold down against the floor of the tube. When the tube was turned on, the cathode rays cast a sharp cross-shaped shadow on the fluorescence on the back face of the tube, showing that the rays moved in straight lines. This fluorescence was used as an argument that cathode rays were electromagnetic waves, since the only thing known to cause fluorescence at the time was ultraviolet light. After a while the fluorescence would get 'tired' and the glow would decrease. If the cross was folded down out of the path of the rays, it no longer cast a shadow, and the previously shadowed area would fluoresce more strongly than the area around it. === Perpendicular emission === Eugen Goldstein in 1876 found that cathode rays were always emitted perpendicular to the cathode's surface. If the cathode was a flat plate, the rays were shot out in straight lines perpendicular to the plane of the plate. This was evidence that they were particles, because a luminous object, like a


id: crookes-tube-20260505-3
file: data/en.wikipedia.org/wiki/Crookes_tube-3.md
category: reference
title: Crookes tube
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crookes_tube
date_saved: 2026-05-05T09:36:41.769217+00:00
instance: kb-cron
parent: crookes-tube-20260505-0
summary:
=== Spectral shift === Eugen Goldstein thought he had figured out a method of measuring the speed of cathode rays. If the glow discharge seen in the gas of Crookes tubes was produced by the moving cathode rays, the light radiated from them in the direction they were moving, down the tube, would be shifted in frequency due to the Doppler effect. This could be detected with a spectroscope because the emission line spectrum would be shifted. He built a tube shaped like an "L", with a spectroscope pointed through the glass of the elbow down one of the arms. He measured the spectrum of the glow when the spectroscope was pointed toward the cathode end, then switched the power supply connections so the cathode became the anode and the electrons were moving in the other direction, and again observed the spectrum looking for a shift. He did not find one, which he calculated meant that the rays were traveling very slowly. It was later recognized that the glow in Crookes tubes is emitted from gas atoms hit by the electrons, not the electrons themselves. Since the atoms are thousands of times more massive than the electrons, they move much


id: cyanometer-20260505-0
file: data/en.wikipedia.org/wiki/Cyanometer-0.md
category: reference
title: Cyanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cyanometer
date_saved: 2026-05-05T09:36:45.088006+00:00
instance: kb-cron
parent: cyanometer-20260505-0
summary:
A cyanometer (from cyan and -meter) is an instrument for measuring "blueness", specifically the colour intensity of blue sky. It is attributed to Horace-Bénédict de Saussure and Alexander von Humboldt. It consists of squares of paper dyed in graduated shades of blue and arranged in a color circle or square that can be held up and compared to the color of the sky. == History == Horace-Bénédict de Saussure, a Swiss physicist and mountain climber, is credited with inventing the cyanometer in the 1760s. De Saussure's cyanometer was divided into colored, numbered sections, ranging from white to gradually darker shades of blue, dyed with Prussian blue and arranged in a circle. The cyanometers were manually produced with a predefined recipe of watercolor concentration for each section, and then distributed to friends and fellow naturalists to gather more observations. In an article from 1790, de Saussure presents an illustration of a wheel with 40 stops, though clarifies that it serves merely to give the reader "an idea of its form"; the actual cyanometer had 53 stops (or "degrees"), starting with white as 0 and black as 52. De Saussure believed that the color of the sky was dependent on the amount


id: eise-eisinga-planetarium-20260505-0
file: data/en.wikipedia.org/wiki/Eise_Eisinga_Planetarium-0.md
category: reference
title: Eise Eisinga Planetarium
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eise_Eisinga_Planetarium
date_saved: 2026-05-05T09:36:50.802517+00:00
instance: kb-cron
parent: eise-eisinga-planetarium-20260505-0
summary:
The Royal Eise Eisinga Planetarium (Dutch: Koninklijk Eise Eisinga Planetarium) is an 18th-century orrery in Franeker, Friesland, Netherlands. It is currently a museum and open to the public. The orrery has been on the top 100 Dutch heritage sites list since 1990. In September 2023, it received the status of UNESCO World Heritage Site. It is the oldest working orrery in the world. == History == The orrery was built from 1774 to 1781 by Eise Eisinga, a wool carder and amateur astronomer. Eise Eisinga’s mechanical planetarium is built into the timber roof of the living room ceiling of his historic canal house. William I, Prince of Orange and the first King of the Netherlands, was so impressed with the planetarium, he purchased the house and it became a royal planetarium. The museum consists of the planetarium room, a screening room where documentaries are shown, and special exhibits based on modern astronomy. Other parts on permanent display are Eisinga’s former wool combing establishments and a collection of historical astronomical instruments. Those instruments in the collection include Georgian telescopes, 18th century octants and a tellurium, an educational model of the Sun, Earth and Moon. The museum has a Planetarium Café and


id: electric-bath-electrotherapy-20260505-0
file: data/en.wikipedia.org/wiki/Electric_bath_(electrotherapy)-0.md
category: reference
title: Electric bath (electrotherapy)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electric_bath_(electrotherapy)
date_saved: 2026-05-05T09:36:52.142335+00:00
instance: kb-cron
parent: electric-bath-electrotherapy-20260505-0
summary:
An electric bath is a 19th-century medical treatment in which high-voltage electrical apparatus was used for electrifying patients by causing an electric charge to build up on their bodies. In the US this process was known as Franklinization after Benjamin Franklin. The process became widely known after Franklin described it in the mid-18th century, but after that it was mostly practiced by quacks. Golding Bird brought it into the mainstream at Guy's Hospital in the mid-19th century and it fell into disuse in the early 20th century. == Description == The source of electricity for an electric bath was usually a frictional electrical machine. The patient was seated on a wooden stool, and both the patient and the stool insulated from ground by a platform on glass legs or some other insulator. In some arrangements, the patient was lying down rather than seated. The patient was then charged with static electricity either by direct connection to one electrode of the generator (usually the positive), or else through electrostatic induction by holding a large electrode close to the patient's body. The electric tension applied was around 30–50 kV. Treatment could take several hours. Following charging the patient was "bathed" in electricity,


id: electrostatic-generator-20260505-0
file: data/en.wikipedia.org/wiki/Electrostatic_generator-0.md
category: reference
title: Electrostatic generator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrostatic_generator
date_saved: 2026-05-05T09:36:55.653201+00:00
instance: kb-cron
parent: electrostatic-generator-20260505-0
summary:
An electrostatic generator, or electrostatic machine, is an electrical generator that produces static electricity, or electricity at high voltage and low continuous current. The knowledge of static electricity dates back to the earliest civilizations, but for millennia it remained merely an interesting and mystifying phenomenon, without a theory to explain its behavior and often confused with magnetism. By the end of the 17th century, researchers had developed practical means of generating electricity by friction, but the development of electrostatic machines did not begin in earnest until the 18th century, when they became fundamental instruments in the studies about the new science of electricity. Electrostatic generators operate by using manual (or other) power to transform mechanical work into electric energy, or using electric currents. Manual electrostatic generators develop electrostatic charges of opposite signs rendered to two conductors, using only electric forces, and work by using moving plates, drums, or belts to carry electric charge to a high potential electrode. == Description == Electrostatic machines are typically used in science classrooms to safely demonstrate electrical forces and high voltage phenomena. The elevated potential differences achieved have also been used for a variety of practical applications, such as operating X-ray tubes, particle accelerators,


id: electrostatic-generator-20260505-1
file: data/en.wikipedia.org/wiki/Electrostatic_generator-1.md
category: reference
title: Electrostatic generator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrostatic_generator
date_saved: 2026-05-05T09:36:55.653201+00:00
instance: kb-cron
parent: electrostatic-generator-20260505-0
summary:
==== Friction operation ==== The presence of surface charge imbalance means that the objects will exhibit attractive or repulsive forces. This surface charge imbalance, which leads to static electricity, can be generated by touching two differing surfaces together and then separating them due to the phenomenon of the triboelectric effect. Rubbing two non-conductive objects can generate a great amount of static electricity. This is not the result of friction; two non-conductive surfaces can become charged by just being placed one on top of the other. Since most surfaces have a rough texture, it takes longer to achieve charging through contact than through rubbing. Rubbing objects together increases amount of adhesive contact between the two surfaces. Usually insulators, e.g., substances that do not conduct electricity, are good at both generating, and holding, a surface charge. Some examples of these substances are rubber, plastic, glass, and pith. Conductive objects in contact generate charge imbalance too, but retain the charges only if insulated. The charge that is transferred during contact electrification is stored on the surface of each object. Note that the presence of electric current does not detract from the electrostatic forces nor from the sparking, from the corona discharge, or other


id: electrostatic-generator-20260505-2
file: data/en.wikipedia.org/wiki/Electrostatic_generator-2.md
category: reference
title: Electrostatic generator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrostatic_generator
date_saved: 2026-05-05T09:36:55.653201+00:00
instance: kb-cron
parent: electrostatic-generator-20260505-0
summary:
In 1878, the British inventor James Wimshurst started his studies about electrostatic generators, improving the Holtz machine, in a powerful version with multiple disks. The classical Wimshurst machine, that became the most popular form of influence machine, was reported to the scientific community by 1883, although previous machines with very similar structures were previously described by Holtz and Musaeus. In 1885, one of the largest-ever Wimshurst machines was built in England (it is now at the Chicago Museum of Science and Industry). The Wimshurst machine is a considerably simple machine; it works, as all influence machines, with electrostatic induction of charges, which means that it uses even the slightest existing charge to create and accumulate more charges, and repeats this process for as long as the machine is in action. Wimshurst machines are composed of: two insulated disks attached to pulleys of opposite rotation, the disks have small conductive (usually metal) plates on their outward-facing sides; two double-ended brushes that serve as charge stabilizers and are also the place where induction happens, creating the new charges to be collected; two pairs of collecting combs, which are, as the name implies, the collectors of electrical charge produced by the machine; two


id: electrostatic-generator-20260505-3
file: data/en.wikipedia.org/wiki/Electrostatic_generator-3.md
category: reference
title: Electrostatic generator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrostatic_generator
date_saved: 2026-05-05T09:36:55.653201+00:00
instance: kb-cron
parent: electrostatic-generator-20260505-0
summary:
The Van de Graaff generator was invented by American physicist Robert J. Van de Graaff in 1929 at MIT as a particle accelerator. The first model was demonstrated in October 1929. In the Van de Graaff machine, an insulating belt transports electric charge to the interior of an insulated hollow metal high voltage terminal, where it is transferred to the terminal by a "comb" of metal points. The advantage of the design was that since there was no electric field in the interior of the terminal, the charge on the belt could continue to be discharged onto the terminal regardless of how high the voltage on the terminal was. Thus the only limit to the voltage on the machine is ionization of the air next to the terminal. This occurs when the electric field at the terminal exceeds the dielectric strength of air, about 30 kV per centimeter. Since the highest electric field is produced at sharp points and edges, the terminal is made in the form of a smooth hollow sphere; the larger the diameter the higher the voltage attained. The first machine used a silk ribbon bought at a five and dime store as the charge transport belt.


id: electrostatic-generator-20260505-4
file: data/en.wikipedia.org/wiki/Electrostatic_generator-4.md
category: reference
title: Electrostatic generator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrostatic_generator
date_saved: 2026-05-05T09:36:55.653201+00:00
instance: kb-cron
parent: electrostatic-generator-20260505-0
summary:
== Further reading == Gottlieb Christoph Bohnenberger: Beschreibung unterschiedlicher Elektrizitätsverdoppler von einer neuen Einrichtung nebst einer Anzahl von Versuchen üb. verschiedene Gegenstände d. Elektrizitätslehre [Description of different electricity-doubler of a new device, along with a number of experiments on various subjects of electricity] Tübingen 1798. Holtz, W. (1865). "Ueber eine neue Elektrisirmaschine" [On a new electrical machine]. Annalen der Physik und Chemie (in German). 202 (9). Wiley: 157–171. Bibcode:1865AnP...202..157H. doi:10.1002/andp.18652020911. ISSN 0003-3804. Wilhelm Holtz: the higher charge on insulating surfaces by side pull and the transfer of this principle to the construction of induction machines .. In: Johann Poggendorff, CG Barth (eds): Annals of physics and chemistry. 130, Leipzig 1867, pp. 128–136 Wilhelm Holtz: The influence machine. In: F. Poske (Eds.): Annals of physics and chemistry. Julius Springer, Berlin 1904 (seventeenth year, the fourth issue). O. Lehmann: Dr. J. Frick's physical technique. 2, Friedrich Vieweg und Sohn, Braunschweig 1909, p. 797 (Section 2). F. Poske: New forms of influence machines. In: F. Poske (eds) for the physical and chemical education. journal Julius Springer, Berlin 1893 (seventh year, second issue). C. L. Stong, "Electrostatic motors are powered by electric field of the Earth". October, 1974. (PDF) Oleg D. Jefimenko, "Electrostatic Motors:


id: an-experiment-on-a-bird-in-the-air-pump-20260505-0
file: data/en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump-0.md
category: reference
title: An Experiment on a Bird in the Air Pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump
date_saved: 2026-05-05T09:37:00.402844+00:00
instance: kb-cron
parent: an-experiment-on-a-bird-in-the-air-pump-20260505-0
summary:
An Experiment on a Bird in the Air Pump is a 1768 oil-on-canvas painting by Joseph Wright of Derby, one of a number of candlelit scenes that Wright painted during the 1760s. The painting departed from convention of the time by depicting a scientific subject in the reverential manner formerly reserved for scenes of historical or religious significance. Wright was intimately involved in depicting the Industrial Revolution and the scientific advances of the Enlightenment. While his paintings were recognized as exceptional by his contemporaries, his provincial status and choice of subjects meant the style was never widely imitated. The picture has been owned by the National Gallery in London since 1863 and is regarded as a masterpiece of British art. The painting depicts a natural philosopher, a forerunner of the modern scientist, recreating one of Robert Boyle's air pump experiments, in which a bird is deprived of air before a group of onlookers. The group members exhibit a variety of reactions, such as grief, disbelief and dismay, but for most of the audience scientific curiosity overcomes concern for the bird. The central figure looks out of the picture as if inviting the viewer's participation in the outcome. The painting was


id: an-experiment-on-a-bird-in-the-air-pump-20260505-1
file: data/en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump-1.md
category: reference
title: An Experiment on a Bird in the Air Pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump
date_saved: 2026-05-05T09:37:00.402844+00:00
instance: kb-cron
parent: an-experiment-on-a-bird-in-the-air-pump-20260505-0
summary:
=== Background === During his apprenticeship and early career Wright concentrated on portraiture. By 1762, he was an accomplished portrait artist, and his 1764 group portrait James Shuttleworth, his Wife and Daughter is acknowledged as his first true masterpiece. Benedict Nicolson suggests that Wright was influenced by the work of Thomas Frye; in particular by the 18 bust-length mezzotints which Frye completed just before his death in 1762. It was perhaps Frye's candlelight images that tempted Wright to experiment with subject pieces. Wright's first attempt, A Girl reading a Letter by Candlelight with a Young Man looking over her shoulder from 1762 or 1763, is a trial in the genre, and is fetching though uncomplicated. Wright's, An Experiment on a Bird in the Air Pump forms part of a series of candlelit nocturnes that he produced between 1765 and 1768. There was a long history of painting candlelit scenes in Western art, although as Wright had not at this date traveled abroad, there remains uncertainty as to what paintings he might have seen in the original, as opposed to prints. Nicolson, who made studies of both Wright and other candlelight painters such as the 17th-century Utrecht Caravaggisti, thought their paintings,


id: an-experiment-on-a-bird-in-the-air-pump-20260505-2
file: data/en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump-2.md
category: reference
title: An Experiment on a Bird in the Air Pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump
date_saved: 2026-05-05T09:37:00.402844+00:00
instance: kb-cron
parent: an-experiment-on-a-bird-in-the-air-pump-20260505-0
summary:
An Experiment on a Bird in the Air Pump followed in 1768, the emotionally charged experiment contrasting with the orderly scene from The Orrery. The painting, which measures 72 by 94½ inches (183 by 244 cm), shows a grey cockatiel fluttering in panic as the air is slowly withdrawn from the vessel by the pump. The witnesses display various emotions: one of the girls worriedly watches the fate of the bird, while the other is too upset to observe and is comforted by her father; two gentlemen (one of them dispassionately timing the experiment) and a boy look on with interest, while the young lovers to the left of the painting are absorbed only in each other. The scientist himself looks directly out of the picture, as if challenging the viewer to judge whether the pumping should continue, killing the bird, or whether the air should be replaced and the cockatiel saved. David Solkin suggests that little sympathy is directed toward the bird; the subjects of the painting show the dispassionate detachment of the evolving scientific society. Individuals are concerned for each other: the father for his children, the young man for the girl, but the distress of the cockatiel


id: an-experiment-on-a-bird-in-the-air-pump-20260505-3
file: data/en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump-3.md
category: reference
title: An Experiment on a Bird in the Air Pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump
date_saved: 2026-05-05T09:37:00.402844+00:00
instance: kb-cron
parent: an-experiment-on-a-bird-in-the-air-pump-20260505-0
summary:
The powerful central light source creates a chiaroscuro effect. The light illuminating the scene has been described as "so brilliant it could only be the light of revelation". The single source of light is obscured behind the bowl on the table; some hint of a lamp glass can be seen around the side of the bowl, but David Hockney has suggested that the bowl itself may contain Sulphur, giving a powerful single light source that a candle or oil lamp would not. In the earlier study a candle holder is visible, and the flame is reflected in the bowl. Hockney believes that many of the Old Masters used optical equipment to assist in their painting, and suggests that Wright may have used lenses to transfer the image to paper rather than painting directly from the scene, as he believes the pattern of shadows thrown by the lighting could have been too complicated for Wright to have captured so accurately without assistance. It may be observed, however, that the stand on which the pump is situated casts no shadow on the body of the philosopher, as it could be expected to do. Wright's Air Pump was unusual in that it depicted


id: an-experiment-on-a-bird-in-the-air-pump-20260505-4
file: data/en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump-4.md
category: reference
title: An Experiment on a Bird in the Air Pump
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/An_Experiment_on_a_Bird_in_the_Air_Pump
date_saved: 2026-05-05T09:37:00.402844+00:00
instance: kb-cron
parent: an-experiment-on-a-bird-in-the-air-pump-20260505-0
summary:
Wright exhibited the painting at the Society of Artists Exhibition of 1768 and it was re-exhibited before Christian VII of Denmark in September the same year. Viewers remarked that it was "clever and vigorous", while Gustave Flaubert, who saw it on a visit to England between 1865 and 1866, considered it "charming in naivety and depth". It was popular enough that a mezzotint was engraved from it by Valentine Green which was published by John Boydell on 24 June 1769, and initially sold for 15 shillings. This was reprinted throughout the 18th and 19th centuries, in increasingly weak impressions. Ellis Waterhouse called it "one of the wholly original masterpieces of British art". From Bates, the picture passed to Walter Tyrell; another member of the Tyrell family, Edward, presented it to the National Gallery, London, in 1863, after it had failed to sell at an auction at Christie's in 1854. The painting was transferred to the Tate Gallery in 1929, although it was actually on loan to Derby Museum and Art Gallery between 1912 and 1947. It has been lent out for exhibitions to the National Gallery of Art in Washington, D.C., in 1976, the National Museum of Fine Arts in


id: franklin-bells-20260505-0
file: data/en.wikipedia.org/wiki/Franklin_bells-0.md
category: reference
title: Franklin bells
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Franklin_bells
date_saved: 2026-05-05T09:37:02.808625+00:00
instance: kb-cron
parent: franklin-bells-20260505-0
summary:
Franklin bells (also known as lightning bells) are an early demonstration of electric charge designed to work with a Leyden jar or a lightning rod. Franklin bells are only a qualitative indicator of electric charge and were used for simple demonstrations rather than research. The bells are an adaptation to the first device that converted electrical energy into mechanical energy in the form of continuous mechanical motion: in this case, the moving of a bell clapper back and forth between two oppositely charged bells. == History == Scientific investigation of the phenomena of lightning originates with Benjamin Franklin. He accumulated analogical evidence favoring the supposition that lightning must be an electrical discharge on a large scale. In the mid-18th century, lightning strikes were a serious problem for buildings and structures, causing damage and sometimes even fires. Franklin set out to understand the nature of lightning and to find ways to protect buildings from its destructive effects. He began his investigations by observing how lightning strikes affected various types of buildings. He noticed that some buildings were more vulnerable to lightning strikes than others and that buildings with sharp pointed roofs were more likely to be struck than those with flat


id: franklin-s-electrostatic-machine-20260505-0
file: data/en.wikipedia.org/wiki/Franklin's_electrostatic_machine-0.md
category: reference
title: Franklin's electrostatic machine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Franklin's_electrostatic_machine
date_saved: 2026-05-05T09:37:04.008946+00:00
instance: kb-cron
parent: franklin-s-electrostatic-machine-20260505-0
summary:
Franklin's electrostatic machine is a high-voltage static electricity-generating device used by Benjamin Franklin in the mid-18th century for research into electrical phenomena. Its key components are a glass globe which turned on an axis via a crank, a cloth pad in contact with the spinning globe, a set of metal needles to conduct away the charge developed on the globe by its friction with the pad, and a Leyden jar – a high-voltage capacitor – to accumulate the charge. Franklin's experiments with the machine eventually led to new theories about electricity and inventing the lightning rod. == Background == Franklin was not the first to build an electrostatic generator. European scientists developed machines to generate static electricity decades earlier. In 1663, Otto von Guericke generated static electricity with a device that used a sphere of sulfur. Francis Hauksbee developed a more advanced electrostatic generator around 1704 using a glass bulb that had a vacuum. He later replaced the globe with a glass tube of about 2.5 feet (0.76 m) emptied of air. The glass tube was a less effective static generator than the globe, but it became more popular because it was easier to use. Machines that generated static electricity


id: franklin-s-electrostatic-machine-20260505-1
file: data/en.wikipedia.org/wiki/Franklin's_electrostatic_machine-1.md
category: reference
title: Franklin's electrostatic machine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Franklin's_electrostatic_machine
date_saved: 2026-05-05T09:37:04.008946+00:00
instance: kb-cron
parent: franklin-s-electrostatic-machine-20260505-0
summary:
== Electrical principles == Franklin's experiments with Leyden jars progressed to connecting several Leyden jars together in a series, with "one hanging on the tail of the other". All of the jars in the series could be charged simultaneously, which multiplied the electrical effect. A similar apparatus had been created earlier by Daniel Gralath. Franklin called this device an "electrical battery", but that term later came to have a different meaning, referring instead to a set of one or more galvanic cells. At that time, the word "battery" was a military term for a group of cannons. Franklin was the first to apply the terms "positive" and "negative" to electricity. Through his research, Franklin was among first to prove the electrical principal of conservation of charge in 1747: a similar discovery was made independently in 1746 by William Watson. Franklin wrote detailed letters and documents about his experiments with the electrostatic machine and Leyden jars. In 1749, Franklin made a list of several ways in which lightning was similar to electricity. He concluded that lightning was essentially nothing more than giant electric sparks, similar to the sparks from the static charges produced by his electrostatic machine. He referred to static


id: franklin-s-electrostatic-machine-20260505-2
file: data/en.wikipedia.org/wiki/Franklin's_electrostatic_machine-2.md
category: reference
title: Franklin's electrostatic machine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Franklin's_electrostatic_machine
date_saved: 2026-05-05T09:37:04.008946+00:00
instance: kb-cron
parent: franklin-s-electrostatic-machine-20260505-0
summary:
Franklin distributed copies of the electrostatic machine to many of his close associates to encourage them to study electricity. Between 1747 and 1750, Franklin sent many letters to his friend Collinson in London about his experiments with the electrostatic machine and the Leyden jar, including his observations and theories on the principles of electricity. These letters were collected and published in 1751 in a book entitled Experiments and Observations on Electricity. While Joseph Priestley was writing about the history of electricity, Franklin encouraged him to use an electrostatic machine to perform the experiments he was writing about. Priestly designed and used his own variations of Franklin's machine. While replicating the electrical experiments, some unanswered questions prompted Priestly to design additional experiments, leading to additional discoveries. In 1767, he published a 700-page book on his findings called The History and Present State of Electricity. Eighteenth-century scientific laboratories usually contained some form of hand-operated electrostatic machine. Italian scientist Luigi Galvani had an electrostatic generator in his laboratory, where experiments with frog legs led him to conclude that animals generated a vital force, an animal electricity. Another Italian scientist, Alessandro Volta, disagreed with Galvani's claim that the electrical effects were due to something


id: groma-surveying-20260505-0
file: data/en.wikipedia.org/wiki/Groma_(surveying)-0.md
category: reference
title: Groma (surveying)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Groma_(surveying)
date_saved: 2026-05-05T09:37:08.672050+00:00
instance: kb-cron
parent: groma-surveying-20260505-0
summary:
The groma (as standardized in the imperial Latin, sometimes croma, or gruma in the literature of the republican times) was a surveying instrument used in the Roman Empire. The groma allowed projecting right angles and straight lines and thus enabling the centuriation (setting up of a rectangular grid). It is the only Roman surveying tool with examples that survive to the present day. == History == The name "groma" came to Latin from the Greek gnoma via the Etruscan language. It is unclear which of the many meanings of the Ancient Greek: γνώμων gnomon (cf. Liddell & Scott, "gnoma" is a form) was used, although in multiple sources the Greek term is used to designate the central point of a camp or town. Dividing the land into rectangular plots was used by the Ancient Greeks, Egyptians and even Mesopotamians. However, the sheer scale of Roman centuriation from the 2nd century BC, when the new colonies were formed mostly to provide for veterans and landless citizens, was unprecedented, so it is not clear to what extent Greek practices influenced the Roman surveyors. The peculiarities of the Roman surveying methods and terminology suggest independence of Roman measurement tradition. The groma may have


id: honcheonsigye-20260505-0
file: data/en.wikipedia.org/wiki/Honcheonsigye-0.md
category: reference
title: Honcheonsigye
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Honcheonsigye
date_saved: 2026-05-05T09:37:09.833489+00:00
instance: kb-cron
parent: honcheonsigye-20260505-0
summary:
The Honcheonsigye (Korean: 혼천시계; Hanja: 渾天時計; lit. 'armillary clock') is an astronomical clock made by Song Yi-Yeong (송이영; 宋以潁), a professor of Gwansanggam (관상감; 觀象監) (one of the scientific institution of Joseon) in 1669. It was designated as South Korean national treasure number 230 in August 9, 1985. The clock used the alarm clock technology created by Christiaan Huygens in 1657. This relic shows that Huygens' technology was spread to East Asia in just 12 years. Also, It demonstrates the astronomy and mechanical engineering technology of the Joseon Dynasty. The clock has an armillary sphere with a diameter of 40 cm. The sphere is activated by a clockwork mechanism, designed to display the position of the heavens at any given time, as well as displaying the hours and marking their passage with a chiming bell. The device is no longer in working order. The clock is owned by Korea University Museum. It is the only remaining astronomical clock from the Joseon period. The clock was purchased from an antiques dealer some time before WWII by Mr Kim Seong-su 김성수 金性洙, the rich businessman and politician who founded Korea University. The historian of science Jeon Sang-Woon 전상운 全相運, who examined the


id: jacob-s-staff-20260505-0
file: data/en.wikipedia.org/wiki/Jacob's_staff-0.md
category: reference
title: Jacob's staff
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Jacob's_staff
date_saved: 2026-05-05T09:37:13.264277+00:00
instance: kb-cron
parent: jacob-s-staff-20260505-0
summary:
Jacob's staff is a measuring tool with several variations. It is also known as cross-staff, a ballastella, a fore-staff, a ballestilla, or a balestilha. In its most basic form, a Jacob's staff is a stick or pole with length markings, often with a smaller segment attached perpendicularly. The simplest use of a Jacob's staff is to make qualitative judgements of the height and angle of an object relative to the user of the staff. Most staffs are much more complicated than that, and usually contain a number of measurement and stabilization features. The two most frequent uses are: in astronomy and navigation for a simple device to measure angles, later replaced by the more precise sextants; in surveying (and scientific fields that use surveying techniques, such as geology and ecology) for a vertical rod that penetrates or sits on the ground and supports a compass or other instrument. == Etymology == The origin of the name of the instrument is not certain. Some refer to the Biblical patriarch Jacob, specifically in the Book of Genesis (Gen 32:11). It may also take its name after its resemblance to Orion, referred to by the name of Jacob on some medieval star charts.


id: jacob-s-staff-20260505-1
file: data/en.wikipedia.org/wiki/Jacob's_staff-1.md
category: reference
title: Jacob's staff
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Jacob's_staff
date_saved: 2026-05-05T09:37:13.264277+00:00
instance: kb-cron
parent: jacob-s-staff-20260505-0
summary:
The original version was not reported to be used at sea, until the Age of Discoveries. Its use was reported by João de Lisboa in his Treatise on the Nautical Needle of 1514. Johannes Werner suggested the cross-staff be used at sea in 1514 and improved instruments were introduced for use in navigation. John Dee introduced it to England in the 1550s. In the improved versions, the rod was graduated directly in degrees. This variant of the instrument is not correctly termed a Jacob's staff but is a cross-staff. The cross-staff was difficult to use. In order to get consistent results, the observer had to position the end of the pole precisely against his cheek. He had to observe the horizon and a star in two different directions while not moving the instrument when he shifted his gaze from one to the other. In addition, observations of the sun required the navigator to look directly at the sun. This could be a uncomfortable exercise and made it difficult to obtain an accurate altitude for the sun. Mariners took to mounting smoked-glass to the ends of the transoms to reduce the glare of the sun. As a navigational tool, this instrument


id: large-electrostatic-generator-teylers-20260505-0
file: data/en.wikipedia.org/wiki/Large_electrostatic_generator_(Teylers)-0.md
category: reference
title: Large electrostatic generator (Teylers)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Large_electrostatic_generator_(Teylers)
date_saved: 2026-05-05T09:37:14.441217+00:00
instance: kb-cron
parent: large-electrostatic-generator-teylers-20260505-0
summary:
The large electrostatic generator (Dutch: Van Marum electriseermachine) is a large handcrafted electromechanical instrument designed by Martin van Marum and built by John Cuthbertson in 1784 for the Teylers Museum in Haarlem, where it forms the centerpiece of the instrument room. The concept of an electrostatic generator was new, and the battery (array) of leiden jars was the largest ever built (only one of the 4 sets of leiden jars is on display to conserve space). The two glass disks of the triboelectric generator (friction generator) are 1.65 meters in diameter, and the machine is capable of generating a potential of 330,000 volts. == History == The device is a larger version of a similar model built in Groningen by Gerhard Kuyper in 1774 for physics student Martin van Marum, who used it to make a name for himself in the study of electricity with his lectures and demonstrations. It was Van Marum's dream to create a larger version, and he applied to the Teylers Stichting in 1783 for funding to create such a large instrument in the hope that it would add a valuable contribution to the science of electricity. On April 11 of that year his request was


id: list-of-surveying-instruments-20260505-0
file: data/en.wikipedia.org/wiki/List_of_surveying_instruments-0.md
category: reference
title: List of surveying instruments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_surveying_instruments
date_saved: 2026-05-05T09:37:16.824358+00:00
instance: kb-cron
parent: list-of-surveying-instruments-20260505-0
summary:
Instruments used in surveying include: Alidade Alidade table Cosmolabe Dioptra Dumpy level Engineer's chain Geodimeter Graphometer Groma (surveying) Laser scanning Level Level staff Measuring tape Plane table Pole (surveying) Prism (surveying) (corner cube retroreflector) Prismatic compass (angle measurement) Ramsden surveying instruments Ranging rod Surveyor's chain Surveyor's compass Tachymeter (surveying) Tape (surveying) Tellurometer Theodolite Half theodolite Plain theodolite Simple theodolite Great theodolite Non-transit theodolite Transit theodolite Seconds theodolite Electronic theodolite Mining theodolite Suspension theodolite Traveling theodolite Pibal theodolite Registering theodolite Gyro-theodolite Construction theodolite Photo-theodolite Robotic theodolite Vernier theodolite Total station Transit (surveying) Tripod (surveying) Universal instrument (surveying) == See also == Astronomical instrument Measurement instrument == Further reading == Lewis, M. J. T. (2001-04-23). Surveying Instruments of Greece and Rome. Cambridge University Press. doi:10.1017/cbo9780511483035. ISBN 978-0-521-79297-4.


id: magdeburg-hemispheres-20260505-0
file: data/en.wikipedia.org/wiki/Magdeburg_hemispheres-0.md
category: reference
title: Magdeburg hemispheres
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Magdeburg_hemispheres
date_saved: 2026-05-05T09:37:18.037607+00:00
instance: kb-cron
parent: magdeburg-hemispheres-20260505-0
summary:
The Magdeburg hemispheres are a pair of large copper hemispheres with mating rims that were used in a famous 1654 experiment to demonstrate the power of atmospheric pressure. When the rims were sealed with grease and the air was pumped out, the sphere contained a vacuum and could not be pulled apart by teams of horses. Once the valve was opened, air rushed in and the hemispheres were easily separated. The Magdeburg hemispheres were invented by German scientist and mayor of Magdeburg, Otto von Guericke, to demonstrate the air pump that he had invented and the concept of atmospheric pressure. Speculation varied about the contents of the sphere. Many thought it was simply empty, while others argued the vacuum contained air or some finer aerial substance. Sound did not transmit through the sphere, indicating that sound needed a medium in order to travel and/or be sensed, while light did not. The first artificial vacuum had been produced a few years earlier by Evangelista Torricelli and inspired Guericke to design the world's first vacuum pump, which consisted of a piston and cylinder with one-way flap valves. The hemispheres became popular in physics lectures as an illustration of the strength of air


id: maxwell-s-thermodynamic-surface-20260505-0
file: data/en.wikipedia.org/wiki/Maxwell's_thermodynamic_surface-0.md
category: reference
title: Maxwell's thermodynamic surface
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Maxwell's_thermodynamic_surface
date_saved: 2026-05-05T09:37:20.383670+00:00
instance: kb-cron
parent: maxwell-s-thermodynamic-surface-20260505-0
summary:
Maxwell's thermodynamic surface is an 1874 sculpture made by Scottish physicist James Clerk Maxwell (1831–1879). This model provides a three-dimensional space of the various states of a fictitious substance with water-like properties. This plot has coordinates volume (x), entropy (y), and energy (z). It was based on the American scientist Josiah Willard Gibbs’ graphical thermodynamics papers of 1873. In Maxwell's words, the model allowed "the principal features of known substances [to] be represented on a convenient scale." == Construction of the model == Gibbs' papers defined what Gibbs called the "thermodynamic surface," which expressed the relationship between the volume, entropy, and energy of a substance at different temperatures and pressures. However, Gibbs did not include any diagrams of this surface. After receiving reprints of Gibbs' papers, Maxwell recognized the insight afforded by Gibbs' new point of view and set about constructing physical three-dimensional models of the surface. This reflected Maxwell's talent as a strong visual thinker and prefigured modern scientific visualization techniques. Maxwell sculpted the original model in clay and made several plaster casts of the clay model, sending one to Gibbs as a gift, keeping two in his laboratory at Cambridge University. Maxwell's copy is on display at the


id: nonius-device-20260505-0
file: data/en.wikipedia.org/wiki/Nonius_(device)-0.md
category: reference
title: Nonius (device)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nonius_(device)
date_saved: 2026-05-05T09:37:25.100904+00:00
instance: kb-cron
parent: nonius-device-20260505-0
summary:
Nonius is a measuring tool used in navigation and astronomy named in honour of its inventor, Pedro Nunes (Latin: Petrus Nonius), a Portuguese author, mathematician and navigator. The nonius was created in 1542 as a system for taking finer measurements on circular instruments such as the astrolabe. The system was eventually adapted into the Vernier scale in 1631 by the French mathematician Pierre Vernier. == Technical features == The nonius was used to improve the astrolabe's accuracy. This consisted of a number of concentric circles traced on an instrument and dividing each successive one with one fewer divisions than the adjacent outer circle. On a standard scale of 90 degrees, there are an additional 44–45 concentric circles, with each divided into a specific unit size such that a scale unit on position n {\displaystyle n} had an arc of 90 / n {\displaystyle 90/n} degrees. Thus, the outermost quadrant would comprise 90° in 90 equal divisions, the next inner would have 89 divisions, the next 88 and so on. When an angle was measured, the circle and the division on which the alidade fell was noted. A table was then consulted to provide the exact measure. == Applications == The


id: passemant-astronomical-clock-20260505-0
file: data/en.wikipedia.org/wiki/Passemant_astronomical_clock-0.md
category: reference
title: Passemant astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Passemant_astronomical_clock
date_saved: 2026-05-05T09:37:29.815736+00:00
instance: kb-cron
parent: passemant-astronomical-clock-20260505-0
summary:
The Passemant astronomical clock is an astronomical clock designed by Claude-Simeon Passemant in the eighteenth century. It is displayed in the Salon de la pendule in the petit appartement du roi on the first floor of Versailles, France. The clock set the official time in France for the first time in the kingdom's history. == Description == The clock is an exceptional rococo work over 2 metres (6 ft 7 in) in height, crowned with a moving celestial sphere. It shows the date, time, real time average phases of the moon and Copernican planetary motion. The large astronomical dials mark the rising and setting of the sun and moon every day. Earth is represented by a bronze globe on which all countries are engraved with the main cities. This globe is placed among the rocks and waterfalls, which serve as a universal horizon. The mechanism is designed to be able to display the date until the end of the year 9999. == Creators == The clock mechanism was designed by engineer Claude-Siméon Passemant (1702–1769) and executed by the clockmaker Louis Dauthiau (1730–1809). The rococo-style gilt-bronze box protecting the mechanism was made in 1753 by sculptor Jean-Jacques Caffieri (1735–1792) and bronze-founder


id: a-philosopher-lecturing-on-the-orrery-20260505-0
file: data/en.wikipedia.org/wiki/A_Philosopher_Lecturing_on_the_Orrery-0.md
category: reference
title: A Philosopher Lecturing on the Orrery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/A_Philosopher_Lecturing_on_the_Orrery
date_saved: 2026-05-05T09:37:31.008006+00:00
instance: kb-cron
parent: a-philosopher-lecturing-on-the-orrery-20260505-0
summary:
A Philosopher Lecturing on the Orrery, or the full title, A Philosopher giving that Lecture on the Orrery in which a lamp is put in place of the Sun, is a 1766 painting by Joseph Wright of Derby depicting a lecturer giving a demonstration of an orrery – a mechanical model of the Solar System – to a small audience. It is now in the Derby Museum and Art Gallery The painting preceded his similar An Experiment on a Bird in the Air Pump (National Gallery, London). The first of Wright's candlelit masterpieces, Three Persons Viewing the Gladiator by Candlelight, was painted in 1765, and showed three men studying a small copy of the "Borghese Gladiator". The Gladiator was greatly admired; but his next painting, The Orrery, caused a greater stir, as it replaced the Classical subject at the centre of the scene with one of a scientific nature. Wright's depiction of the awe produced by scientific "miracles" marked a break with previous traditions in which the artistic depiction of such wonder was reserved for religious events, since to Wright the marvels of the technological age were as awe-inspiring as the subjects of the great religious paintings. In both of


id: plane-table-20260505-0
file: data/en.wikipedia.org/wiki/Plane_table-0.md
category: reference
title: Plane table
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plane_table
date_saved: 2026-05-05T09:37:32.218499+00:00
instance: kb-cron
parent: plane-table-20260505-0
summary:
A plane table (plain table prior to 1830) is a device used in surveying, site mapping, exploration mapping, coastal navigation mapping, and related disciplines to provide a solid and level surface on which to make field drawings, charts and maps. The early use of the name plain table reflected its simplicity and plainness rather than its flatness. "Plane" refers to the table being both flat and levelled (horizontal). == History == The earliest mention of a plane table dates to 1551 in Abel Foullon's "Usage et description de l'holomètre", published in Paris. However, since Foullon's description was of a complete, fully developed instrument, it must have been invented earlier. A brief description was also added to the 1591 edition of Digge's Pantometria. The first mention of the device in English was by Cyprian Lucar in 1590. The Swiss instrument maker Leonhard Zubler published an account of the plane table in Novum instrumentum geometricum, 1607. He used the term Instrumentum Chorographicum crediting its invention to Philipp Eberhard, a fellow Swiss instrument maker based in Zurich. Some have credited Johann Richter, also known as Johannes Praetorius, a Nuremberg mathematician, in 1610 with the first plane table, but this appears to be incorrect.


id: radio-latino-20260505-0
file: data/en.wikipedia.org/wiki/Radio_latino-0.md
category: reference
title: Radio latino
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Radio_latino
date_saved: 2026-05-05T09:37:36.860302+00:00
instance: kb-cron
parent: radio-latino-20260505-0
summary:
A radio latino is a measuring instrument used in surveying and military engineering starting in the 16th century. It gets its name from the inventor, Latino Orsini. The radio latino can be considered a kind of geometric square. It was a general purpose instrument that could be used for a variety of angular measurements as well as depth and inside dimension measures. == Usage == The slider (blue in the adjacent diagram) could move along the central rod, causing the deltoid formed by four other rods to change shape symmetrically. The end points of the rods had sights on them, allowing various sight lines to be defined. The central rod was graduated with various scales. These scales allowed the angles between the end rods (represented by the red lines in the diagram) to be determined as well as the angle with its vertex at one end of the main rod and sides (represented by the green lines in the diagram) through the outer joints of the rods. With different graduations, one could determine or lay out: angles between sight lines with a degree scale. internal angles of regular polygons with polygon scales. internal diameters and dimensions (such as the inside


id: ramsden-surveying-instruments-20260505-0
file: data/en.wikipedia.org/wiki/Ramsden_surveying_instruments-0.md
category: reference
title: Ramsden surveying instruments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ramsden_surveying_instruments
date_saved: 2026-05-05T09:37:38.027690+00:00
instance: kb-cron
parent: ramsden-surveying-instruments-20260505-0
summary:
The Ramsden surveying instruments are those constructed by Jesse Ramsden and used in high precision geodetic surveys carried out in the period 1784 to 1853. This includes the five great theodolites—great in name, great in size and great in accuracy—used in surveys of Britain and other parts of the world. Ramsden also provided the equipment used in the measurement of the many base lines of these surveys and also the zenith telescope used in latitude determinations. == The great theodolites == A total of eight such instruments were manufactured by Ramsden and others for use in Britain, India and Switzerland. Ramsden himself constructed three theodolites and a further two were completed to his design by Mathew Berge, his son-in-law and business successor, after Ramsden's death in 1805. Of the other instruments one was constructed by William Cary and the other two by the firm of Troughton & Simms. === The Royal Society theodolite === In 1783 the Royal Society of London reacted to (unfounded) French criticism of Greenwich Observatory by seeking Royal assent to undertake a high precision geodetic survey, the Anglo-French Survey (1784–1790), between Greenwich and the established French survey stations on the other side of the English Channel.


id: ramsden-surveying-instruments-20260505-1
file: data/en.wikipedia.org/wiki/Ramsden_surveying_instruments-1.md
category: reference
title: Ramsden surveying instruments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ramsden_surveying_instruments
date_saved: 2026-05-05T09:37:38.027690+00:00
instance: kb-cron
parent: ramsden-surveying-instruments-20260505-0
summary:
=== Great theodolites by other builders === Although the East India Company turned down Ramsden's second theodolite, they commissioned a similar design from another London instrument maker, William Cary. This theodolite was in use in India from 1802 although there was a slight hiatus in 1808 when it was damaged when being hauled to the top of a building. It was repaired and in use for sixty years. A new theodolite to an improved design was made for the Indian Survey by Troughton and Simms in 1830 and the two together saw service until 1874 when the Cary instrument was replaced by another by Troughton and Sims. This last instrument was a monster weighing 1,455 lb (660 kg) when in its travelling cases: it was no surprise that it was deemed too heavy for transport up mountains and it passed to South Africa in 1882. No more great instruments were made after 1874 for continuing advances in precision instruments eclipsed their performance: by the end of the nineteenth century an accuracy of 1 arc second could be obtained with a 12-inch (300 mm) instrument. == Chains and rods == Eighteenth-century surveyors used Gunter's chains which were 22 yards long (one


id: slide-rule-20260505-0
file: data/en.wikipedia.org/wiki/Slide_rule-0.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
A slide rule is a hand-operated mechanical calculator consisting of slidable rulers for conducting mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry. It is one of the simplest analog computers. Slide rules exist in a diverse range of styles and generally appear in a linear, circular or cylindrical form. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in specialized calculations particular to those fields. The slide rule is closely related to nomograms used for application-specific computations. Though similar in name and appearance to a standard ruler, the slide rule is not meant to be used for measuring length or drawing straight lines. Maximum accuracy for standard linear slide rules is about three decimal significant digits, while scientific notation is used to keep track of the order of magnitude of results. English mathematician and clergyman Reverend William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. It made calculations faster and less error-prone than evaluating on paper. Before the advent of the scientific pocket calculator, it was the most commonly used calculation tool in science and engineering.


id: slide-rule-20260505-1
file: data/en.wikipedia.org/wiki/Slide_rule-1.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
But since the 7 is above the second set of numbers that number must be multiplied by 10. Thus, even though the answer directly reads 1.4, the correct answer is 1.4×10 = 14. For an example with even larger numbers, to multiply 88×20, the top scale is again positioned to start at the 2 on the bottom scale. Since 2 represents 20, all numbers in that scale are multiplied by 10. Thus, any answer in the second set of numbers is multiplied by 100. Since 8.8 in the top scale represents 88, the answer must additionally be multiplied by 10. The answer directly reads 1.76. Multiply by 100 and then by 10 to get the actual answer: 1,760. In general, the 1 on the top is moved to a factor on the bottom, and the answer is read off the bottom where the other factor is on the top. This works because the distances from the 1 mark are proportional to the logarithms of the marked values. ==== Division ==== The illustration below demonstrates the computation of ⁠5.5/2⁠. The 2 on the top scale is placed over the 5.5 on the bottom scale. The resulting quotient, 2.75, can then be


id: slide-rule-20260505-2
file: data/en.wikipedia.org/wiki/Slide_rule-2.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
==== Future value of money ==== The LLN scales can be used to compute and compare the cost or return on a fixed rate loan or investment. The simplest case is for continuously compounded interest. Example: Taking D as the interest rate in percent, slide the index (the "1" at the right or left end of the scale) of C to the percent on D. The corresponding value on LL2 directly below the index will be the multiplier for 10 cycles of interest (typically years). The value on LL2 below 2 on the C scale will be the multiplier after 20 cycles, and so on. ==== Trigonometry ==== The S, T, and ST scales are used for trig functions and multiples of trig functions, for angles in degrees. For angles from around 5.7 up to 90 degrees, sines are found by comparing the S scale with C (or D) scale. (On many closed-body rules the S scale relates to the A and B scales instead and covers angles from around 0.57 up to 90 degrees; what follows must be adjusted appropriately.) The S scale has a second set of angles (sometimes in a different color), which run in the opposite


id: slide-rule-20260505-3
file: data/en.wikipedia.org/wiki/Slide_rule-3.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
Circular slide rules come in two basic types, one with two cursors, and another with a free dish and one cursor. The dual cursor versions perform multiplication and division by holding a constant angle between the cursors as they are rotated around the dial. The onefold cursor version operates more like the standard slide rule through the appropriate alignment of the scales. The basic advantage of a circular slide rule is that the widest dimension of the tool was reduced by a factor of about 3 (i.e. by π). For example, a 10 cm (3.9 in) circular would have a maximum precision approximately equal to a 31.4 cm (12.4 in) ordinary slide rule. Circular slide rules also eliminate "off-scale" calculations, because the scales were designed to "wrap around"; they never have to be reoriented when results are near 1.0—the rule is always on scale. However, for non-cyclical non-spiral scales such as S, T, and LL's, the scale width is narrowed to make room for end margins. Circular slide rules are mechanically more rugged with smoother motion, but their scale alignment precision is sensitive to the centering of a central pivot; a minute 0.1 mm (0.0039 in) off-centre of the pivot


id: slide-rule-20260505-4
file: data/en.wikipedia.org/wiki/Slide_rule-4.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
The slide rule was invented around 1620–1630, shortly after John Napier's publication of the concept of the logarithm. In 1620 Edmund Gunter of Oxford developed a calculating device with a single logarithmic scale; with additional measuring tools it could be used to multiply and divide. In c. 1622, William Oughtred of Cambridge combined two handheld Gunter rules to make a device that is recognizably the modern slide rule. Oughtred became involved in a vitriolic controversy over priority, with his one-time student Richard Delamain and the prior claims of Edmund Wingate. Oughtred's ideas were only made public in publications of his student William Forster in 1632 and 1653. In 1677, Henry Coggeshall created a two-foot folding rule for timber measure, called the Coggeshall slide rule, expanding the slide rule's use beyond mathematical inquiry. In 1722, Warner introduced the two- and three-decade scales, and in 1755 Everard included an inverted scale; a slide rule containing all of these scales is usually known as a "polyphase" rule. In 1815, Peter Mark Roget invented the log log slide rule, which included a scale displaying the logarithm of the logarithm. This allowed the user to directly perform calculations involving roots and exponents. This was especially


id: slide-rule-20260505-5
file: data/en.wikipedia.org/wiki/Slide_rule-5.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
=== Specialized calculators === Slide rules have often been specialized to varying degrees for their field of use, such as excise, proof calculation, engineering, navigation, etc., and some slide rules are extremely specialized for very narrow applications. For example, the John Rabone & Sons 1892 catalog lists a "Measuring Tape and Cattle Gauge", a device to estimate the weight of a cow from its measurements. There were many specialized slide rules for photographic applications. For example, the actinograph of Hurter and Driffield was a two-slide boxwood, brass, and cardboard device for estimating exposure from time of day, time of year, and latitude. Specialized slide rules were invented for various forms of engineering, business and banking. These often had common calculations directly expressed as special scales, for example loan calculations, optimal purchase quantities, or particular engineering equations. For example, the Fisher Controls company distributed a customized slide rule adapted to solving the equations used for selecting the proper size of industrial flow control valves. Pilot balloon slide rules were used by meteorologists in weather services to determine the upper wind velocities from an ascending hydrogen or helium-filled pilot balloon. The E6-B is a circular slide rule used by pilots and navigators.


id: slide-rule-20260505-6
file: data/en.wikipedia.org/wiki/Slide_rule-6.md
category: reference
title: Slide rule
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule
date_saved: 2026-05-05T09:37:44.876699+00:00
instance: kb-cron
parent: slide-rule-20260505-0
summary:
Even during their heyday, slide rules never caught on with the general public. Addition and subtraction are not well-supported operations on slide rules and doing a calculation on a slide rule tends to be slower than on a calculator. This led engineers to use mathematical equations that favored operations that were easy on a slide rule over more accurate but complex functions; these approximations could lead to inaccuracies and mistakes. On the other hand, the spatial, manual operation of slide rules cultivates in the user an intuition for numerical relationships and scale that people who have used only digital calculators often lack. A slide rule will also display all the terms of a calculation along with the result, thus eliminating uncertainty about what calculation was actually performed. It has thus been compared with reverse Polish notation (RPN) implemented in electronic calculators. A slide rule requires the user to separately compute the order of magnitude of the answer to position the decimal point in the results. For example, 1.5 × 30 (which equals 45) will show the same result as 1500000 × 0.03 (which equals 45000). This separate calculation forces the user to keep track of magnitude in short-term memory (which


id: slide-rule-scale-20260505-0
file: data/en.wikipedia.org/wiki/Slide_rule_scale-0.md
category: reference
title: Slide rule scale
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Slide_rule_scale
date_saved: 2026-05-05T09:37:46.082245+00:00
instance: kb-cron
parent: slide-rule-scale-20260505-0
summary:
A slide rule scale is a line with graduated markings inscribed along the length of a slide rule used for mathematical calculations. The earliest such device had a single logarithmic scale for performing multiplication and division, but soon an improved technique was developed which involved two such scales sliding alongside each other. Later, multiple scales were provided with the most basic being logarithmic but with others graduated according to the mathematical function required. Few slide rules have been designed for addition and subtraction, rather the main scales are used for multiplication and division and the other scales are for mathematical calculations involving trigonometric, exponential and, generally, transcendental functions. Before they were superseded by electronic calculators in the 1970s, slide rules were an important type of portable calculating instrument. == Slide rule design == A slide rule consists of a body and a slider that can be slid along within the body and both of these have numerical scales inscribed on them. On duplex rules the body and/or the slider have scales on the back as well as the front. The slider's scales may be visible from the back or the slider may need to be slid right out and replaced


id: string-galvanometer-20260505-0
file: data/en.wikipedia.org/wiki/String_galvanometer-0.md
category: reference
title: String galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/String_galvanometer
date_saved: 2026-05-05T09:38:01.968350+00:00
instance: kb-cron
parent: string-galvanometer-20260505-0
summary:
A string galvanometer is a sensitive fast-responding measuring instrument that uses a single fine filament of wire suspended in a strong magnetic field to measure small currents. In use, a strong light source is used to illuminate the fine filament, and the optical system magnifies the movement of the filament allowing it to be observed or recorded by photography. The principle of the string galvanometer remained in use for electrocardiograms until the advent of electronic vacuum-tube amplifiers in the 1920s. == History == Submarine cable telegraph systems of the late 19th century used a galvanometer to detect pulses of electric current, which could be observed and transcribed into a message. The speed at which pulses could be detected by the galvanometer was limited by its mechanical inertia, and by the inductance of the multi-turn coil used in the instrument. Clément Adair, a French engineer, replaced the coil with a much faster wire or "string" producing the first string galvanometer. For most telegraphic purposes it was sufficient to detect the existence of a pulse. In 1892 André Blondel described the dynamic properties of an instrument that could measure the wave shape of an electrical impulse, an oscillograph. Augustus Waller had discovered


id: surveyor-s-wheel-20260505-0
file: data/en.wikipedia.org/wiki/Surveyor's_wheel-0.md
category: reference
title: Surveyor's wheel
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Surveyor's_wheel
date_saved: 2026-05-05T09:38:03.094892+00:00
instance: kb-cron
parent: surveyor-s-wheel-20260505-0
summary:
A surveyor's wheel, also called a clickwheel, hodometer, waywiser, trundle wheel, measuring wheel or perambulator is a device for measuring distance. == Origin == The origins of the surveyor's wheel are connected to the origins of the odometer. While the latter is derived to measure distances travelled by a vehicle, the former is specialized to measure general distances. In the 17th century, the surveyor's wheel was introduced and used to measure distances. A single wheel is attached to a handle and the device can be pushed or pulled along by a person walking. Early devices were made of wood and may have had an iron rim to provide strength. The wheels themselves would be made in the same manner as wagon wheels and often by the same makers. The measuring devices would be made by makers of scientific instruments and the device and handles would be attached to the wheel by them. The device to read the distance travelled would be mounted either near the hub of the wheel or at the top of the handle. In some cases, double-wheel hodometers were constructed. Francis Ronalds extended the concept in 1827 to create a device that recorded the distances travelled in


id: transversal-instrument-making-20260505-0
file: data/en.wikipedia.org/wiki/Transversal_(instrument_making)-0.md
category: reference
title: Transversal (instrument making)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transversal_(instrument_making)
date_saved: 2026-05-05T09:38:06.602771+00:00
instance: kb-cron
parent: transversal-instrument-making-20260505-0
summary:
Transversals are a geometric construction on a scientific instrument to allow a graduation to be read to a finer degree of accuracy. Their use creates what is sometimes called a diagonal scale, an engineering measuring instrument which is composed of a set of parallel straight lines which are obliquely crossed by another set of straight lines. Diagonal scales are used to measure small fractions of the unit of measurement. Transversals have been replaced in modern times by vernier scales. This method is based on the Intercept theorem (also known as Thales's theorem). == History == Transversals were used at a time when finely graduated instruments were difficult to make. They were found on instruments starting in the early 14th century, but the inventor is unknown. In 1342 Levi Ben Gerson introduced an instrument called Jacob's staff (apparently invented the previous century by Jacob Ben Makir) and described the method of the transversal scale applied to the mentioned instrument. Thomas Digges mistakenly attributed the discovery of the transversal scale to the navigator and explorer Richard Chancellor (cited by some authors as watchmaker and with other names, among them: Richard Chansler or Richard Kantzler). Its use on astronomical instruments only began in


id: history-of-scientific-method-20260505-0
file: data/en.wikipedia.org/wiki/History_of_scientific_method-0.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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parent: history-of-scientific-method-20260505-0
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The history of scientific method considers changes in the methodology of scientific inquiry, as distinct from the history of science itself. The development of rules for scientific reasoning has not been straightforward; scientific method has been the subject of intense and recurring debate throughout the history of science, and eminent natural philosophers and scientists have argued for the primacy of one or another approach to establishing scientific knowledge. Rationalist explanations of nature, including atomism, appeared both in ancient Greece in the thought of Leucippus and Democritus, and in ancient India, in the Nyaya, Vaisheshika and Buddhist schools, while Charvaka materialism rejected inference as a source of knowledge in favour of an empiricism that was always subject to doubt. Aristotle pioneered scientific method in ancient Greece alongside his empirical biology and his work on logic, rejecting a purely deductive framework in favour of generalisations made from observations of nature. Some of the most important debates in the history of scientific method center on: rationalism, especially as advocated by René Descartes; inductivism, which rose to particular prominence with Isaac Newton and his followers; and hypothetico-deductivism, which came to the fore in the early 19th century. In the late 19th and early 20th


id: history-of-scientific-method-20260505-1
file: data/en.wikipedia.org/wiki/History_of_scientific_method-1.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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=== Aristotle === Aristotle's inductive-deductive method used inductions from observations to infer general principles, deductions from those principles to check against further observations, and more cycles of induction and deduction to continue the advance of knowledge. The Organon (Greek: Ὄργανον, meaning "instrument, tool, organ") is the standard collection of Aristotle's six works on logic. The name Organon was given by Aristotle's followers, the Peripatetics. The order of the works is not chronological (the chronology is now difficult to determine) but was deliberately chosen by Theophrastus to constitute a well-structured system. Indeed, parts of them seem to be a scheme of a lecture on logic. The arrangement of the works was made by Andronicus of Rhodes around 40 BCE. The Organon comprises the following six works: The Categories (Greek: Κατηγορίαι, Latin: Categoriae) introduces Aristotle's 10-fold classification of that which exists: substance, quantity, quality, relation, place, time, situation, condition, action, and passion. On Interpretation (Greek: Περὶ Ἑρμηνείας, Latin: De Interpretatione) introduces Aristotle's conception of proposition and judgment, and the various relations between affirmative, negative, universal, and particular propositions. Aristotle discusses the square of opposition or square of Apuleius in Chapter 7 and its appendix Chapter 8. Chapter 9 deals with the problem


id: history-of-scientific-method-20260505-2
file: data/en.wikipedia.org/wiki/History_of_scientific_method-2.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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=== Epicurus === In his work Kαvώv ('canon', a straight edge or ruler, thus any type of measure or standard, referred to as 'canonic'), Epicurus laid out his first rule for inquiry in physics: 'that the first concepts be seen, and that they not require demonstration '. His second rule for inquiry was that prior to an investigation, we are to have self-evident concepts, so that we might infer [ἔχωμεν οἷς σημειωσόμεθα] both what is expected [τò προσμένον], and also what is non-apparent [τò ἄδηλον]. Epicurus applies his method of inference (the use of observations as signs, Asmis' summary, p. 333: the method of using the phenomena as signs (σημεῖα) of what is unobserved) immediately to the atomic theory of Democritus. In Aristotle's Prior Analytics, Aristotle himself employs the use of signs. But Epicurus presented his 'canonic' as rival to Aristotle's logic. See: Lucretius (c. 99 BCE – c. 55 BCE) De rerum natura (On the nature of things) a didactic poem explaining Epicurus' philosophy and physics. == Emergence of inductive experimental method == During the Middle Ages issues of what is now termed science began to be addressed. There was greater emphasis on combining theory with practice in the


id: history-of-scientific-method-20260505-3
file: data/en.wikipedia.org/wiki/History_of_scientific_method-3.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
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=== Al-Biruni === The Persian scientist Abū Rayhān al-Bīrūnī introduced early scientific methods for several different fields of inquiry during the 1020s and 1030s. For example, in his treatise on mineralogy, Kitab al-Jawahir (Book of Precious Stones), al-Biruni is "the most exact of experimental scientists", while in the introduction to his study of India, he declares that "to execute our project, it has not been possible to follow the geometric method" and thus became one of the pioneers of comparative sociology in insisting on field experience and information. He also developed an early experimental method for mechanics. Al-Biruni's methods resembled the modern scientific method, particularly in his emphasis on repeated experimentation. Biruni was concerned with how to conceptualize and prevent both systematic errors and observational biases, such as "errors caused by the use of small instruments and errors made by human observers." He argued that if instruments produce errors because of their imperfections or idiosyncratic qualities, then multiple observations must be taken, analyzed qualitatively, and on this basis, arrive at a "common-sense single value for the constant sought", whether an arithmetic mean or a "reliable estimate." In his scientific method, "universals came out of practical, experimental work" and "theories are


id: history-of-scientific-method-20260505-4
file: data/en.wikipedia.org/wiki/History_of_scientific_method-4.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
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=== Renaissance humanism and medicine === Aristotle's ideas became a framework for critical debate beginning with absorption of the Aristotelian texts into the university curriculum in the first half of the 13th century. Contributing to this was the success of medieval theologians in reconciling Aristotelian philosophy with Christian theology. Within the sciences, medieval philosophers were not afraid of disagreeing with Aristotle on many specific issues, although their disagreements were stated within the language of Aristotelian philosophy. All medieval natural philosophers were Aristotelians, but "Aristotelianism" had become a somewhat broad and flexible concept. With the end of Middle Ages, the Renaissance rejection of medieval traditions coupled with an extreme reverence for classical sources led to a recovery of other ancient philosophical traditions, especially the teachings of Plato. By the 17th century, those who clung dogmatically to Aristotle's teachings were faced with several competing approaches to nature. The discovery of the Americas at the close of the 15th century showed the scholars of Europe that new discoveries could be found outside of the authoritative works of Aristotle, Pliny, Galen, and other ancient writers. Galen of Pergamon (129 – c. 200 AD) had studied with four schools in antiquity — Platonists, Aristotelians, Stoics,


id: history-of-scientific-method-20260505-5
file: data/en.wikipedia.org/wiki/History_of_scientific_method-5.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
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The first modern science, in which practitioners were prepared to revise or reject long-held beliefs in the light of new evidence, was astronomy, and Tycho Brahe was the first modern astronomer. See Sextant, right. Note the explicit reduction of geometrical diagrams to practice (real objects with actual lengths and angles). In 1572, Tycho noticed a completely new star that was brighter than any star or planet. Astonished by the existence of a star that ought not to have been there and gaining the patronage of King Frederick II of Denmark, Tycho built the Uraniborg observatory at enormous cost. Over a period of fifteen years (1576–1591), Tycho and upwards of thirty assistants charted the positions of stars, planets, and other celestial bodies at Uraniborg with unprecedented accuracy. In 1600, Tycho hired Johannes Kepler to assist him in analyzing and publishing his observations. Kepler later used Tycho's observations of the motion of Mars to deduce the laws of planetary motion, which were later explained in terms of Newton's law of universal gravitation. Besides Tycho's specific role in advancing astronomical knowledge, Tycho's single-minded pursuit of ever-more-accurate measurement was enormously influential in creating a modern scientific culture in which theory and evidence were understood


id: history-of-scientific-method-20260505-6
file: data/en.wikipedia.org/wiki/History_of_scientific_method-6.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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In 1619, René Descartes began writing his first major treatise on proper scientific and philosophical thinking, the unfinished Rules for the Direction of the Mind. His aim was to create a complete science that he hoped would overthrow the Aristotelian system and establish himself as the sole architect of a new system of guiding principles for scientific research. This work was continued and clarified in his 1637 treatise, Discourse on Method, and in his 1641 Meditations. Descartes describes the intriguing and disciplined thought experiments he used to arrive at the idea we instantly associate with him: I think therefore I am. From this foundational thought, Descartes finds proof of the existence of a God who, possessing all possible perfections, will not deceive him provided he resolves "[...] never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgment than what was presented to my mind so clearly and distinctly as to exclude all ground of methodic doubt." This rule allowed Descartes to progress beyond his own thoughts and judge that there exist extended bodies outside of his own


id: history-of-scientific-method-20260505-7
file: data/en.wikipedia.org/wiki/History_of_scientific_method-7.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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parent: history-of-scientific-method-20260505-0
summary:
Both Bacon and Descartes wanted to provide a firm foundation for scientific thought that avoided the deceptions of the mind and senses. Bacon envisaged that foundation as essentially empirical, whereas Descartes provides a metaphysical foundation for knowledge. If there were any doubts about the direction in which scientific method would develop, they were set to rest by the success of Isaac Newton. Implicitly rejecting Descartes' emphasis on rationalism in favor of Bacon's empirical approach, he outlines his four "rules of reasoning" in the Principia, We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances. Therefore to the same natural effects we must, as far as possible, assign the same causes. The qualities of bodies, which admit neither intension nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever. In experimental philosophy we are to look upon propositions collected by general induction from phænomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, until such time as other phænomena occur, by which they may


id: history-of-scientific-method-20260505-8
file: data/en.wikipedia.org/wiki/History_of_scientific_method-8.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
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parent: history-of-scientific-method-20260505-0
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"In order to achieve completeness in our knowledge of nature, we must start from two extremes, from experience and from the intellect itself. ... The former method must conclude with natural laws, which it has abstracted from experience, while the latter must begin with principles, and gradually, as it develops more and more, it becomes ever more detailed. Of course, I speak here about the method as manifested in the process of the human intellect itself, not as found in textbooks, where the laws of nature which have been abstracted from the consequent experiences are placed first because they are required to explain the experiences. When the empiricist in his regression towards general laws of nature meets the metaphysician in his progression, science will reach its perfection." Ørsted's "First Introduction to General Physics" (1811) exemplified the steps of observation, hypothesis, deduction and experiment. In 1805, based on his researches on electromagnetism Ørsted came to believe that electricity is propagated by undulatory action (i.e., fluctuation). By 1820, he felt confident enough in his beliefs that he resolved to demonstrate them in a public lecture, and in fact observed a small magnetic effect from a galvanic circuit (i.e., voltaic circuit), without rehearsal;


id: history-of-scientific-method-20260505-9
file: data/en.wikipedia.org/wiki/History_of_scientific_method-9.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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parent: history-of-scientific-method-20260505-0
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In the late 19th century, Charles Sanders Peirce proposed a schema that would turn out to have considerable influence in the further development of scientific method generally. Peirce's work quickly accelerated the progress on several fronts. Firstly, speaking in broader context in "How to Make Our Ideas Clear" (1878), Peirce outlined an objectively verifiable method to test the truth of putative knowledge on a way that goes beyond mere foundational alternatives, focusing upon both Deduction and Induction. He thus placed induction and deduction in a complementary rather than competitive context (the latter of which had been the primary trend at least since David Hume a century before). Secondly, and of more direct importance to scientific method, Peirce put forth the basic schema for hypothesis-testing that continues to prevail today. Extracting the theory of inquiry from its raw materials in classical logic, he refined it in parallel with the early development of symbolic logic to address the then-current problems in scientific reasoning. Peirce examined and articulated the three fundamental modes of reasoning that play a role in scientific inquiry today, the processes that are currently known as abductive, deductive, and inductive inference. Thirdly, he played a major role in the progress


id: history-of-scientific-method-20260505-10
file: data/en.wikipedia.org/wiki/History_of_scientific_method-10.md
category: reference
title: History of scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/History_of_scientific_method
date_saved: 2026-05-05T09:38:13.002530+00:00
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Investigation, or the art of inquiring into the nature of causes and their operation, is a leading characteristic of reason [...] Investigation implies three things – Observation, Hypothesis, and Experiment [...] The first step in the process, it will be perceived, is to observe... In 1885, the words "Scientific method" appear together with a description of the method in Francis Ellingwood Abbot's 'Scientific Theism', Now all the established truths which are formulated in the multifarious propositions of science have been won by the use of Scientific Method. This method consists in essentially three distinct steps (1) observation and experiment, (2) hypothesis, (3) verification by fresh observation and experiment. The Eleventh Edition of Encyclopædia Britannica did not include an article on scientific method; the Thirteenth Edition listed scientific management, but not method. By the Fifteenth Edition, a 1-inch article in the Micropædia of Britannica was part of the 1975 printing, while a fuller treatment (extending across multiple articles, and accessible mostly via the index volumes of Britannica) was available in later printings. == Current issues == In the past few centuries, some statistical methods have been developed, for reasoning in the face of uncertainty, as an outgrowth of methods for eliminating


id: timeline-of-the-history-of-the-scientific-method-20260505-0
file: data/en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method-0.md
category: reference
title: Timeline of the history of the scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method
date_saved: 2026-05-05T09:38:14.255635+00:00
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This timeline of the history of the scientific method shows an overview of the development of the scientific method up to the present time. For a detailed account, see History of the scientific method. == BC == c.1600 BC – The Edwin Smith Papyrus, a unique ancient Egyptian text, contains practical and objective advice to physicians regarding the examination, diagnosis, treatment and prognosis, of injuries and ailments. It provides evidence that medicine in Egypt was at this time practiced as a quantifiable science. c. 600 – 700 BC – The earliest form of Charvaka practiced by philosopher Ajita Kesakambali. c. 600 – 200 BC – The Vaisheshika school of Hindu philosophy, founded by the ancient Indian philosopher Kanada, accepted perception and inference as the only two reliable sources of knowledge. c. 624 – 548 BC – Thales of Miletus raises the study of nature from the realm of the mythical to the level of empirical study. c. 610 – 547 BC – The Greek philosopher Anaximander extends the idea of law from human society to the physical world, and is the first to use maps and models. c.400 BC – In China, the philosopher Mozi founds the Mohist school of


id: timeline-of-the-history-of-the-scientific-method-20260505-1
file: data/en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method-1.md
category: reference
title: Timeline of the history of the scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method
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== 1200–1700 == 1220–1235 – Robert Grosseteste, an English scholastic philosopher, theologian and later the Bishop of Lincoln during 1253, publishes his Aristotelian commentaries, laying out the framework for the proper methods of science. 1265 – The English monk Roger Bacon, inspired by the writings of Robert Grosseteste, describes a scientific method based on a repeating cycle of observation, hypothesis, experimentation, and the need for independent verification. He recorded the manner in which he conducted his experiments in precise detail so that others could reproduce and independently test his results. 1327 – Ockham's razor appears, a principle which states that among competing hypotheses, the one with the fewest assumptions should be selected. 1408 – The Yongle Encyclopedia (Chinese: 永樂大典), the largest encyclopedia in book form ever made, is completed. 1558 - Magia Naturalis, a work of popular science by Giambattista della Porta, is published. In the preface, the author wrote: "In our method I shall observe what our ancestors have said; then I shall show by my own experience, whether they be true or false... Many men have written what they never saw..." 1581 – The sceptic Francisco Sanches uses classical sceptical arguments to show that science, in the Aristotelian


id: timeline-of-the-history-of-the-scientific-method-20260505-2
file: data/en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method-2.md
category: reference
title: Timeline of the history of the scientific method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Timeline_of_the_history_of_the_scientific_method
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1905 – The German-born theoretical physicist Albert Einstein proposes the theory of special relativity. 1926 – Randomized design is popularized and analyzed by the British statistician Ronald Fisher. 1934 – Falsifiability as a criterion for evaluating new hypotheses is popularized by Karl Popper's The Logic of Scientific Discovery . 1937 – The first complete placebo trial is undertaken. The American pharmacologist Harry Gold, studying the effect of xanthines on cardiac pain, alternates them with a placebo and shows them to be ineffective. 1946 – Work begins on the first computer simulation in history, a digital flight simulator developed by the Massachusetts Institute of Technology, for training bomber crews. 1950 – Research based on the double blind test is published for the first time, by Greiner et al. 1962 – The American physicist Thomas S. Kuhn publishes his book The Structure of Scientific Revolutions, which controversially challenged powerful and entrenched philosophical assumptions about the progress of science through history. 1964 – Strong inference—a model of scientific inquiry that emphasizes the need for alternative hypotheses—is proposed by the American physicist John R. Platt. 1976 – The British-born, professor emeritus of statistics at the University of Wisconsin–Madison George E. P. Box publishes his


id: ibn-al-haytham-20260505-0
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-0.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
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parent: ibn-al-haytham-20260505-0
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Ibn al-Haytham, Latinized as Alhazen (c. 965 – c. 1040), was a mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq. Referred to as "the father of modern optics", he made significant contributions to the principles of optics and visual perception in particular. His most influential work is titled Kitāb al-Manāẓir (Arabic: كتاب المناظر, 'Book of Optics'), written during 1011–1021, which survived in a Latin edition. The works of Alhazen were frequently cited during the Scientific Revolution by Galileo Galilei, René Descartes, Johannes Kepler, and Christiaan Huygens. Ibn al-Haytham was the first to correctly prove vision as intromissive rather than extramissive, and to argue that vision occurs in the brain, pointing to observations that it is subjective and affected by personal experience. He also stated the principle of least time for refraction which would later become Fermat's principle. He made major contributions to catoptrics and dioptrics by studying reflection, refraction and nature of images formed by light rays. He was the first physicist to give complete statement of the law of reflection. Ibn al-Haytham was an early proponent of the concept that a hypothesis must be supported by experiments based on confirmable procedures or mathematical reasoning –


id: ibn-al-haytham-20260505-1
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-1.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
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parent: ibn-al-haytham-20260505-0
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Two major theories on vision prevailed in classical antiquity. The first theory, the emission theory, was supported by such thinkers as Euclid and Ptolemy, who believed that sight worked by the eye emitting rays of light. The second theory, the intromission theory supported by Aristotle and his followers, had physical forms entering the eye from an object. Previous Islamic writers (such as al-Kindi) had argued essentially on Euclidean, Galenist, or Aristotelian lines. The strongest influence on the Book of Optics was from Ptolemy's Optics, while the description of the anatomy and physiology of the eye was based on Galen's account. Alhazen's achievement was to come up with a theory that successfully combined parts of the mathematical ray arguments of Euclid, the medical tradition of Galen, and the intromission theories of Aristotle. Alhazen's intromission theory followed al-Kindi (and broke with Aristotle) in asserting that "from each point of every colored body, illuminated by any light, issue light and color along every straight line that can be drawn from that point". This left him with the problem of explaining how a coherent image was formed from many independent sources of radiation; in particular, every point of an object would send rays to


id: ibn-al-haytham-20260505-2
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-2.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
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parent: ibn-al-haytham-20260505-0
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Alhazen's most original contribution was that, after describing how he thought the eye was anatomically constructed, he went on to consider how this anatomy would behave functionally as an optical system. His understanding of pinhole projection from his experiments appears to have influenced his consideration of image inversion in the eye, which he sought to avoid. He maintained that the rays that fell perpendicularly on the lens (or glacial humor as he called it) were further refracted outward as they left the glacial humor and the resulting image thus passed upright into the optic nerve at the back of the eye. He followed Galen in believing that the lens was the receptive organ of sight, although some of his work hints that he thought the retina was also involved. Alhazen's synthesis of light and vision adhered to the Aristotelian scheme, exhaustively describing the process of vision in a logical, complete fashion. His research in catoptrics (the study of optical systems using mirrors) was centred on spherical and parabolic mirrors and spherical aberration. He made the observation that the ratio between the angle of incidence and refraction does not remain constant, and investigated the magnifying power of a lens. === Law


id: ibn-al-haytham-20260505-3
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-3.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
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parent: ibn-al-haytham-20260505-0
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=== Refractometer === In the seventh tract of his book of optics, Alhazen described an apparatus for experimenting with various cases of refraction, in order to investigate the relations between the angle of incidence, the angle of refraction and the angle of deflection. This apparatus was a modified version of an apparatus used by Ptolemy for similar purpose. === Unconscious inference === Alhazen basically states the concept of unconscious inference in his discussion of colour before adding that the inferential step between sensing colour and differentiating it is shorter than the time taken between sensing and any other visible characteristic (aside from light), and that "time is so short as not to be clearly apparent to the beholder." Naturally, this suggests that the colour and form are perceived elsewhere. Alhazen goes on to say that information must travel to the central nerve cavity for processing and:the sentient organ does not sense the forms that reach it from the visible objects until after it has been affected by these forms; thus it does not sense color as color or light as light until after it has been affected by the form of color or light. Now the affectation received by the


id: ibn-al-haytham-20260505-4
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-4.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
instance: kb-cron
parent: ibn-al-haytham-20260505-0
summary:
Therefore, the seeker after the truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration, and not to the sayings of a human being whose nature is fraught with all kinds of imperfection and deficiency. The duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and ... attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency. An aspect associated with Alhazen's optical research is related to systemic and methodological reliance on experimentation (iḵtibār) (Arabic: اختبار) and controlled testing in his scientific inquiries. Moreover, his experimental directives rested on combining classical physics (ilm tabi'i) with mathematics (ta'alim; geometry in particular). This mathematical-physical approach to experimental science supported most of his propositions in Kitab al-Manazir (The Optics; De aspectibus or Perspectivae) and grounded his theories of vision,


id: ibn-al-haytham-20260505-5
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-5.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
instance: kb-cron
parent: ibn-al-haytham-20260505-0
summary:
Ptolemy assumed an arrangement (hay'a) that cannot exist, and the fact that this arrangement produces in his imagination the motions that belong to the planets does not free him from the error he committed in his assumed arrangement, for the existing motions of the planets cannot be the result of an arrangement that is impossible to exist... [F]or a man to imagine a circle in the heavens, and to imagine the planet moving in it does not bring about the planet's motion. Having pointed out the problems, Alhazen appears to have intended to resolve the contradictions he pointed out in Ptolemy in a later work. Alhazen believed there was a "true configuration" of the planets that Ptolemy had failed to grasp. He intended to complete and repair Ptolemy's system, not to replace it completely. In the Doubts Concerning Ptolemy Alhazen set out his views on the difficulty of attaining scientific knowledge and the need to question existing authorities and theories: Truth is sought for itself [but] the truths, [he warns] are immersed in uncertainties [and the scientific authorities (such as Ptolemy, whom he greatly respected) are] not immune from error... He held that the criticism of existing theories – which


id: ibn-al-haytham-20260505-6
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-6.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
instance: kb-cron
parent: ibn-al-haytham-20260505-0
summary:
=== Engineering === In engineering, one account of his career as a civil engineer has him summoned to Egypt by the Fatimid Caliph, Al-Hakim bi-Amr Allah, to regulate the flooding of the Nile River. He carried out a detailed scientific study of the annual inundation of the Nile River, and he drew plans for building a dam, at the site of the modern-day Aswan Dam. His field work, however, later made him aware of the impracticality of this scheme, and he soon feigned madness so he could avoid punishment from the Caliph. === Philosophy === In his Treatise on Place, Alhazen disagreed with Aristotle's view that nature abhors a void, and he used geometry in an attempt to demonstrate that place (al-makan) is the imagined three-dimensional void between the inner surfaces of a containing body. Abd-el-latif, a supporter of Aristotle's philosophical view of place, later criticized the work in Fi al-Radd 'ala Ibn al-Haytham fi al-makan (A refutation of Ibn al-Haytham's place) for its geometrization of place. Alhazen also discussed space perception and its epistemological implications in his Book of Optics. In "tying the visual perception of space to prior bodily experience, Alhazen unequivocally rejected the intuitiveness of spatial perception


id: ibn-al-haytham-20260505-7
file: data/en.wikipedia.org/wiki/Ibn_al-Haytham-7.md
category: reference
title: Ibn al-Haytham
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ibn_al-Haytham
date_saved: 2026-05-05T09:38:17.876632+00:00
instance: kb-cron
parent: ibn-al-haytham-20260505-0
summary:
In 2014, the "Hiding in the Light" episode of Cosmos: A Spacetime Odyssey, presented by Neil deGrasse Tyson, focused on the accomplishments of Ibn al-Haytham. He was voiced by Alfred Molina in the episode. Over forty years previously, Jacob Bronowski presented Alhazen's work in a similar television documentary (and the corresponding book), The Ascent of Man. In episode 5 (The Music of the Spheres), Bronowski remarked that in his view, Alhazen was "the one really original scientific mind that Arab culture produced", whose theory of optics was not improved on till the time of Isaac Newton and Gottfried Wilhelm Leibniz. UNESCO declared 2015 the International Year of Light and its Director-General Irina Bokova dubbed Ibn al-Haytham 'the father of optics'. Amongst others, this was to celebrate Ibn Al-Haytham's achievements in optics, mathematics and astronomy. An international campaign, created by the 1001 Inventions organisation, titled 1001 Inventions and the World of Ibn Al-Haytham featuring a series of interactive exhibits, workshops and live shows about his work, partnering with science centers, science festivals, museums, and educational institutions, as well as digital and social media platforms. The campaign also produced and released the short educational film 1001 Inventions and the World of Ibn


id: john-of-st-amand-20260505-0
file: data/en.wikipedia.org/wiki/John_of_St_Amand-0.md
category: reference
title: John of St Amand
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/John_of_St_Amand
date_saved: 2026-05-05T09:38:19.078504+00:00
instance: kb-cron
parent: john-of-st-amand-20260505-0
summary:
John of St Amand, Canon of Tournay (c. 1230 – 1303), also known as Jean de Saint-Amand and Johannes de Sancto Amando, was a medieval author on pharmacology, teaching at the University of Paris. He wrote treatises on a variety of topics including magnetism and experimental method. == Writings == Among St Amand's many treatises was one on the magnet. His pharmacopoeia was the Commentary on the Antedotary of Nicholas. Like Roger Bacon (c. 1219 – c. 1292) after him, St Amand wrote on experimental method. The historian of science Lynn Thorndike explains that St Amand "asserts that experimentum alone is 'timorous and fallacious', but that 'fortified by reason' it gives 'experimental knowledge'". In his view, what St Amand meant was that experimentation had to be methodical, and used alongside theory. On simples used in herbal medicine, St Amand stated specific rules for practical testing: he advised that the specimen had to be pure; that the test should be on a simple disease; that the test be repeated; and that the dose should depend on the patient. Thorndike notes that both St Amand and Albertus Magnus preceded Bacon in their use of the phrase "experimental knowledge". == References ==


id: novum-organum-20260505-0
file: data/en.wikipedia.org/wiki/Novum_Organum-0.md
category: reference
title: Novum Organum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Novum_Organum
date_saved: 2026-05-05T09:38:21.436473+00:00
instance: kb-cron
parent: novum-organum-20260505-0
summary:
The Novum Organum, fully Novum Organum, sive Indicia Vera de Interpretatione Naturae ("New organon, or true directions concerning the interpretation of nature") or Instaurationis Magnae, Pars II ("Part II of The Great Instauration"), is a philosophical work by Francis Bacon, written in Latin and published in 1620. The title is a reference to Aristotle's work Organon, which was his treatise on logic and syllogism. In Novum Organum, Bacon details a new system of logic he believes to be superior to the old ways of syllogism. This is now known as the Baconian method. For Bacon, finding the essence of a thing was a simple process of reduction, and the use of inductive reasoning. In finding the cause of a "phenomenal nature" such as heat, one must list all of the situations where heat is found. Then another list should be drawn up, listing situations that are similar to those of the first list except for the lack of heat. A third table lists situations where heat can vary. The "form nature", or cause, of heat must be that which is common to all instances in the first table, is lacking from all instances of the second table and varies by


id: novum-organum-20260505-1
file: data/en.wikipedia.org/wiki/Novum_Organum-1.md
category: reference
title: Novum Organum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Novum_Organum
date_saved: 2026-05-05T09:38:21.436473+00:00
instance: kb-cron
parent: novum-organum-20260505-0
summary:
In many of his aphorisms, Bacon reiterates the importance of inductive reasoning. Induction, methodologically prior to deduction, entails beginning with particular cases observed by the senses and then attempting to discover the general axioms from those observations. Thus, induction presupposes the possibility of intelligent sensory observation. Deduction, on the other hand, begins with general axioms ("highest" or "middle"), which might be viewed as first principles or as inductively derived principles, on the basis of which it is possible to derive a systematic, i.e., scientific, knowledge of things. Bacon claims that there are two, and only two, distinct modes of induction and that the second allegedly distinct mode – which he claims will be a "new" way or method, supposedly newly discovered or invented by himself – will be much better than the old one: There are and can only be two ways of investigating and discovering truth. The one rushes up from the sense and particulars to axioms of the highest generality and, from these principles and their indubitable truth, goes on to infer and discover middle axioms; and this is the way in current use. The other way draws axioms from the sense and particulars by climbing steadily and


id: novum-organum-20260505-2
file: data/en.wikipedia.org/wiki/Novum_Organum-2.md
category: reference
title: Novum Organum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Novum_Organum
date_saved: 2026-05-05T09:38:21.436473+00:00
instance: kb-cron
parent: novum-organum-20260505-0
summary:
== Book II == After enumerating the shortcomings of the current and past natural philosophies, Bacon can now present his own philosophy and methods. Bacon retains the Aristotelian causes, but redefines them in interesting ways. While traditionally the final cause was held as most important among the four (material, formal, efficient, and final), Bacon claims that it is the least helpful and in some cases actually detrimental to the sciences (aph. 2). For Bacon, it is the formal cause which is both the most illusive and most valuable, although each of the causes provides certain practical devices. By forms and formal causes, Bacon means the universal laws of nature. To these Bacon attaches an almost occult like power: But he who knows forms grasps the unity of nature beneath the surface of materials which are very unlike. Thus is he able to identify and bring about things that have never been done before, things of the kind which neither the vicissitudes of nature, nor hard experimenting, nor pure accident could ever have actualised, or human thought dreamed of. And thus from the discovery of the forms flows true speculation and unrestricted operation (aphorism 3). In this second book, Bacon offers


id: novum-organum-20260505-3
file: data/en.wikipedia.org/wiki/Novum_Organum-3.md
category: reference
title: Novum Organum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Novum_Organum
date_saved: 2026-05-05T09:38:21.436473+00:00
instance: kb-cron
parent: novum-organum-20260505-0
summary:
Man, the servant and interpreter of nature, does and understands only as much as he has observed, by fact or mental activity, concerning the order of nature; beyond that he has neither knowledge nor power. So, in a basic sense the central difference between the philosophical methods of Descartes and those of Bacon can be reduced to an argument between deductive and inductive reasoning and whether to trust or doubt the senses. However, there is another profound difference between the two thinkers' positions on the accessibility of Truth. Descartes professed to be aiming at absolute Truth. It is questionable whether Bacon believed such a Truth can be achieved. In his opening remarks, he proposes "to establish progressive stages of certainty". For Bacon, a measure of truth was its power to allow predictions of natural phenomena (although Bacon's forms come close to what we might call "Truth", because they are universal, immutable laws of nature). == Original contributions == An interesting characteristic of Bacon's apparently scientific tract was that, although he amassed an overwhelming body of empirical data, he did not make any original discoveries. Indeed, that was never his intention, and such an evaluation of Bacon's legacy may wrongfully lead


id: 1674-in-science-20260505-0
file: data/en.wikipedia.org/wiki/1674_in_science-0.md
category: reference
title: 1674 in science
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/1674_in_science
date_saved: 2026-05-05T09:38:25.171463+00:00
instance: kb-cron
parent: 1674-in-science-20260505-0
summary:
The year 1674 in science and technology involved some significant events. == Biology == Antonie van Leeuwenhoek discovers infusoria using the microscope. == Pharmacology == Thomas Willis publishes Pharmaceutice rationalis. == Births == == Deaths == Jean Pecquet, French anatomist (born 1622) == References ==


id: 1809-in-paleontology-20260505-0
file: data/en.wikipedia.org/wiki/1809_in_paleontology-0.md
category: reference
title: 1809 in paleontology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/1809_in_paleontology
date_saved: 2026-05-05T09:38:26.683120+00:00
instance: kb-cron
parent: 1809-in-paleontology-20260505-0
summary:
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1809. == Pterosaurs == === New taxa === == References ==


id: david-s-adams-biologist-20260505-0
file: data/en.wikipedia.org/wiki/David_S._Adams_(biologist)-0.md
category: reference
title: David S. Adams (biologist)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/David_S._Adams_(biologist)
date_saved: 2026-05-05T09:38:27.894354+00:00
instance: kb-cron
parent: david-s-adams-biologist-20260505-0
summary:
David S. Adams is a Professor of Biology at Worcester Polytechnic Institute. == Education == In 1974, Adams received his BS in physiology from Oklahoma State University. In 1976, he obtained his MS in Biophysical Sciences from the University of Houston. In 1979, he obtained his PhD Molecular Biology from the University of Texas. From 1979 to 1984 Adams received his Postdoc in Molecular Biology from Rockefeller University, New York City. == Alzheimer's Disease research == In 1995, he was the first person to successfully replicate Alzheimer's disease in a mouse. His work in the field suggests that an over-abundance of protein production causes the disease, as opposed to "twists" in neurons, as is alternately argued. The finding remains one of the most significant discoveries in Alzheimer's research to date. == Worcester Polytechnic Institute == Adams lectures multiple biology classes at Worcester Polytechnic Institute, notably Cell Biology, Virology, and Advanced Cell Biology. He is an avid supporter of abolishing textbooks for upper classes, due to his belief that memorization does not contribute to a greater understanding of biology. == Awards and honors == He was elected in 2008 a Fellow of the American Association for the Advancement of Science. ==


id: antonina-le-niewska-museum-of-pharmacy-20260505-0
file: data/en.wikipedia.org/wiki/Antonina_Leśniewska_Museum_of_Pharmacy-0.md
category: reference
title: Antonina Leśniewska Museum of Pharmacy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antonina_Leśniewska_Museum_of_Pharmacy
date_saved: 2026-05-05T09:38:29.042014+00:00
instance: kb-cron
parent: antonina-le-niewska-museum-of-pharmacy-20260505-0
summary:
Muzeum Farmacji im. Antoniny Leśniewskiej w Warszawie is a museum of pharmacy in Warsaw, Poland. It is a branch of the Museum of Warsaw. It was established in 1985. Exhibits include original pharmaceutical laboratory equipment from the 1930s. There are also displays covering the history of Warsaw pharmacies. There are over 2,500 antiquities on display at the museum. == History == The museum opened on 26 January 1985. The sponsor was Antonina Leśniewska, who was experienced in the field of medicine. In 2011, the museum has imported some of the most ancient medical furniture from the 17 and 19th centuries. Some of the oldest antiquities came from archaeological remains from 1602. The museum was nominated for European Museum of the Year in 2022. == References == == External links == Media related to Muzeum Farmacji im. mgr Antoniny Leśniewskiej w Warszawie at Wikimedia Commons Official website


id: astatic-needles-20260505-0
file: data/en.wikipedia.org/wiki/Astatic_needles-0.md
category: reference
title: Astatic needles
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astatic_needles
date_saved: 2026-05-05T09:38:30.277302+00:00
instance: kb-cron
parent: astatic-needles-20260505-0
summary:
An astatic system comprises two equal and parallel magnetic needles, but with their polarities reversed. This arrangement protects the system from the influence of the terrestrial magnetic field, as the magnetisms of the two needles cancel each other out. Because of this phenomenon, astatic needles were often used in galvanometers. == References == "Museo Galileo - object description". "Static Needles - Joseph Henry Project - Princeton University".


id: australian-computer-museum-society-20260505-0
file: data/en.wikipedia.org/wiki/Australian_Computer_Museum_Society-0.md
category: reference
title: Australian Computer Museum Society
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Australian_Computer_Museum_Society
date_saved: 2026-05-05T09:38:31.428896+00:00
instance: kb-cron
parent: australian-computer-museum-society-20260505-0
summary:
The Australian Computer Museum Society Inc, (ACMS) is a society dedicated to the preservation of the history of computing in Australia, including software, hardware, operating systems and literature. ACMS was registered and is a charitable institution which relies on memberships and donations to operate. Established in 1994, their members have since amassed a large number of unique devices designed and built by Australians. == References ==


id: blade-mill-20260505-0
file: data/en.wikipedia.org/wiki/Blade_mill-0.md
category: reference
title: Blade mill
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Blade_mill
date_saved: 2026-05-05T09:38:32.599038+00:00
instance: kb-cron
parent: blade-mill-20260505-0
summary:
A blade mill was a variety of water mill used for sharpening newly fabricated blades, including scythes, swords, sickles, and knives. In the Sheffield area, they were known as cutlers wheels, scythesmiths wheels, etc. Examples are preserved in Abbeydale Industrial Hamlet. They also existed in the 17th century and 18th century in Birmingham and in connection with the scythe industry in Belbroughton and Chaddesley Corbett in north Worcestershire. There were also small numbers in other areas of England. A water wheel was used to turn a grind stone, which wore down from being up to two metres in diameter to a 'cork' of a fraction of this size. The dust generated by the process was bad for the grinder's health, and many of them died young from 'grinder's disease'. == References == "What used to happen at Shepherd Wheel?". Sheffield Industrial Museums Trust. Archived from the original on 2007-10-17.


id: corbett-s-electrostatic-machine-20260505-0
file: data/en.wikipedia.org/wiki/Corbett's_electrostatic_machine-0.md
category: reference
title: Corbett's electrostatic machine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Corbett's_electrostatic_machine
date_saved: 2026-05-05T09:38:33.878318+00:00
instance: kb-cron
parent: corbett-s-electrostatic-machine-20260505-0
summary:
Corbett's electrostatic machine is a static electricity generating device that was made by the Shaker physician Thomas Corbett in 1810. Intended to treat rheumatism, the device built up a static charge and stored it in a Leyden jar, an early type of capacitor. == Description == Corbett was a medical physician for the Shakers, a religious group of colonial America. He was a botanist and preferred herbal medicines to bloodletting. His machine was hand-operated. Rotating a glass cylinder in contact with a silk pad caused a static charge to accumulate on the cylinder. A metal comb collected this charge, which was then stored in a Leyden jar. From the jar, the electrical charge could then be released into the patient, producing a shock akin to "touching a doorknob after walking across carpet in dry weather". == See also == Franklin's electrostatic machine == References ==


id: crell-s-annalen-20260505-0
file: data/en.wikipedia.org/wiki/Crell's_Annalen-0.md
category: reference
title: Crell's Annalen
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crell's_Annalen
date_saved: 2026-05-05T09:38:35.135491+00:00
instance: kb-cron
parent: crell-s-annalen-20260505-0
summary:
Crell's Annalen is a German chemistry journal. It was originally named Chemisches Journal, then Die neuesten Entdeckungen in der Chemie, and later Chemische Annalen für die Freunde der Naturlehre, Arzneygelährtheit, Haushaltungskunst und Manufakturen, which is usually shortened to Chemische Annalen and often referred to as Crell's Annalen after the editor Lorenz Florenz Friedrich von Crell (1744–1816), professor of theoretical medicine and materia medica at the University of Helmstedt; it was first published in 1778. == References == == Further reading == Hufbauer, Karl (1982). The Formation of the German Chemical Community. Berkeley, Los Angeles, London: University of California Press. Reviewed in Lowood, Henry (1984). Eighteenth-Century Studies. 18 (1): 108–112. doi:10.2307/2738316. JSTOR 2738316.{{cite journal}}: CS1 maint: untitled periodical (link)


id: encyclopaedia-cursus-philosophici-20260505-0
file: data/en.wikipedia.org/wiki/Encyclopaedia_Cursus_Philosophici-0.md
category: reference
title: Encyclopaedia Cursus Philosophici
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Encyclopaedia_Cursus_Philosophici
date_saved: 2026-05-05T09:38:36.314315+00:00
instance: kb-cron
parent: encyclopaedia-cursus-philosophici-20260505-0
summary:
The Encyclopaedia Cursus Philosophici is an encyclopedia of Johann Heinrich Alsted (1588–1638). Johann Heinrich Alsted published the Encyclopaedia in seven volumes in 1620 in Herborn. It is often argued that this is the first work to bear the title "encyclopedia", though Joachim Sterck van Ringelbergh's Lucubrationes vel potius absolutissima kyklopaideia was published in 1588, and Paul Scalich published Encyclopediae seu orbis disciplinarum tam sacrarum quam profanarum epistemon in 1559. Alsted was attempting with his Encyclopaedia to emulate the combination system of Ramon Llull as set out in Llull's 1308 Ars Magna, and thus to formulate a system of universal knowledge and a Llullian method for systematising the sciences. The scheme includes categorisations such as: generic - specific; peripheral - central; internal - external; communal - individual; quantum ad locum - ad conditionem ad aetatem; preparatorius - elaboratorius. Alsted's approach influenced, among others, the pedagogue Johann Amos Comenius and the Hungarian encyclopedist Apáczai Csere János (1625–1659). Alsted's vision was that with the right methodologies of teaching and application, any person could have access to a perfect knowledge of all sciences. == Extant copies == There is a copy of the 1630 edition in the Town Library of Ipswich, Suffolk == References


id: epistemic-cultures-20260505-0
file: data/en.wikipedia.org/wiki/Epistemic_cultures-0.md
category: reference
title: Epistemic cultures
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Epistemic_cultures
date_saved: 2026-05-05T09:38:37.466212+00:00
instance: kb-cron
parent: epistemic-cultures-20260505-0
summary:
Epistemic cultures (often used in plural form) is a concept developed in the nineties by anthropologist Karin Knorr Cetina in her book Epistemic Cultures: How the Sciences Make Knowledge. Opposed to a monist vision of scientific activity (according to which, would exist a unique scientific method), Knorr Cetina defines the concept of epistemic cultures as a diversity of scientific activities according to different scientific fields, not only in methods and tools, but also in types of reasonings, ways to establish evidence, and relationships between theory and empiry. Knorr Cetina's work is seminal in questioning the so-called unity of science. == Knorr Cetina's anthropology == In practice, Knorr Cetina compares two contemporary important scientific fields: High energy physics and molecular biology. She worked as an anthropologist within two laboratories, along the line of the laboratory anthropology work by Latour and Woolgar. Her anthropological work is comparative and the two chosen scientific fields are highly mediaticized and easily distinguishable. Epistemic cultures as a philosophical concept has been perused by numerous philosophical, anthropological or historical studies of science. == Two distinct publication regimes == High energy physics and molecular biology are very different as scientific fields belonging to two different epistemic cultures. They


id: euctemon-20260505-0
file: data/en.wikipedia.org/wiki/Euctemon-0.md
category: reference
title: Euctemon
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Euctemon
date_saved: 2026-05-05T09:38:38.679198+00:00
instance: kb-cron
parent: euctemon-20260505-0
summary:
Euctemon (Greek: Εὐκτήμων, gen. Εὐκτήμονος; fl. 432 BC) was an Athenian astronomer. He was a contemporary and collaborator of Meton, who developed the 19-year Metonic cycle, which synchronises 235 lunar months with 19 solar years to form the basis of ancient Greek calendrical systems. Little is known of his work apart from his partnership with Meton and what is mentioned by Ptolemy. With Meton, he made a series of observations of the solstices (the time or date (twice each year) at which the sun reaches its maximum or minimum declination, marked by the longest and shortest days (about 21 June and 22 December) in order to determine the length of the tropical year). Geminus and Ptolemy quote him as a source on the rising and setting of the stars. Pausanias's Description of Greece names Damon and Philogenes as the children of Euctemon. The lunar crater Euctemon is named after him. == References == == External links == The Ancient Library Greek Astronomy Archived 2016-04-07 at the Wayback Machine


id: lucius-tarutius-firmanus-20260505-0
file: data/en.wikipedia.org/wiki/Lucius_Tarutius_Firmanus-0.md
category: reference
title: Lucius Tarutius Firmanus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lucius_Tarutius_Firmanus
date_saved: 2026-05-05T09:38:39.859071+00:00
instance: kb-cron
parent: lucius-tarutius-firmanus-20260505-0
summary:
Lucius Tarutius Firmanus (or Lucius Tarutius of Firmum) (unknown-fl. 86 BC) was a Roman philosopher, mathematician, and astrologer (Taruntius or Tarrutius are also used, but are incorrect). Tarutius was a close friend of both Marcus Terentius Varro and Cicero. At Varro's request, Tarutius took the horoscope of Romulus. After studying the circumstances of the life and death of the founder of Rome, Tarutius calculated that Romulus was born on March 24 (when the date is correctly translated from the Egyptian calendar) in the second year of the second Olympiad (i.e. 771 BC). He also calculated that Rome was founded on 4 October 754 BC, between the second and third hour of the day (Plutarch, Rom., 12; Cicero, De Divin., ii. 47.). The proximity of this date to an eclipse was discussed by Scaliger. The crater Taruntius on the Moon is named after him. == See also == Tarutius == Notes == == External links == (in English) Eduardo Vila-Echagüe, Lucius Tarutius and the foundations of Rome Donne, William Bodham (1870). "Firmanus, Tarutius". In Smith, William (ed.). Dictionary of Greek and Roman Biography and Mythology. Vol. 2. p. 151.


id: samuel-galton-jr-20260505-0
file: data/en.wikipedia.org/wiki/Samuel_Galton_Jr.-0.md
category: reference
title: Samuel Galton Jr.
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Samuel_Galton_Jr.
date_saved: 2026-05-05T09:38:41.013272+00:00
instance: kb-cron
parent: samuel-galton-jr-20260505-0
summary:
Samuel John Galton Jr. FRS (18 June 1753 – 19 June 1832) was an English arms manufacturer. He was born in Duddeston, Birmingham, England, into a Quaker family. He would go on to join his father's gun manufacturing company. He was a member of the Lunar Society in December of 1785 and lived at Great Barr Hall, one of the meeting places for the Lunar Society. He also built a house at Warley Woods, and commissioned Humphry Repton to lay out its grounds. == Family life == Galton married Lucy Barclay (1757–1817), the daughter of Robert Barclay Allardice, MP, 5th of Ury. They would go on to have eight children together. His first born was Mary Anne Galton (1778–1856) who was a writer in the anti-slavery movement. She would marry Lambert Schimmelpenninck in 1806. Galton's second child was Sophia Galton who would go on to marry Charles Brewin. His first son, Samuel Tertius Galton (1783–1844) would also become a member of the Lunar Society. He would end the family arms business in 1815. He married Violetta Darwin in 1807 and had a son named Francis Galton (1822–1911) who would go on to be a famous proponent of eugenics. Galton had


id: green-report-20260505-0
file: data/en.wikipedia.org/wiki/Green_report-0.md
category: reference
title: Green report
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Green_report
date_saved: 2026-05-05T09:38:43.430216+00:00
instance: kb-cron
parent: green-report-20260505-0
summary:
The Green report was written by Andrew Conway Ivy, a medical researcher and vice president of the University of Illinois at Chicago. Ivy was in charge of the medical school and its hospitals. The report justified testing malaria vaccines on Statesville Prison, Joliet, Illinois prisoners in the 1940s. Ivy mentioned the report in the 1946 Nuremberg Medical Trial for Nazi war criminals. He used it to refute any similarity between human experimentation in the United States and the Nazis. == Background == Malaria experiments in the Statesville Prison were publicized in the June 1945 edition of LIFE, entitled "Prisoners Expose Themselves to Malaria". When Ivy testified at the 1946 Nuremberg Medical Trial for Nazi war criminals, he misled the trial about the report, in order to strengthen the prosecution case. Ivy stated that the committee had debated and issued the report, when the committee had not met at that time. It was only formed when Ivy departed for Nuremberg after he requested then Illinois Governor Dwight Green to convene a group that would advise on ethical considerations concerning medical experimentation. An account stated that he wrote the report on his own after he cited its existence in the trial. It


id: hefner-lamp-20260505-0
file: data/en.wikipedia.org/wiki/Hefner_lamp-0.md
category: reference
title: Hefner lamp
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hefner_lamp
date_saved: 2026-05-05T09:38:44.649603+00:00
instance: kb-cron
parent: hefner-lamp-20260505-0
summary:
The Hefner lamp, or in German Hefnerkerze, is a flame lamp used in photometry that burns amyl acetate. The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze (HK). The lamp was specified as having a 40 mm flame height and an 8 mm diameter wick. The Hefner lamp provided the German, Austrian, and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries. The unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height. The light unit was adopted by the German gas industry in 1890 and known as the Hefnereinheit. In 1897 it was also adopted by the Association of German Electrical Engineers under the name Hefnerkerze (HK). Germany moved to using the new candle (NC) from 1 July 1942 and the candela (cd) from 1948. 1 Hefnerkerze is about 0.920 candelas. == See also == Candlepower List of obsolete units of measurement == References == "Lichtstärke und Lichteinheit" (in German). Archived from the original on 2008-04-19.


id: hellenophilia-20260505-0
file: data/en.wikipedia.org/wiki/Hellenophilia-0.md
category: reference
title: Hellenophilia
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hellenophilia
date_saved: 2026-05-05T09:38:45.832393+00:00
instance: kb-cron
parent: hellenophilia-20260505-0
summary:
Hellenophilia is the idea that all western science began in Greek tradition. This is discussed in length by David Pingree in his address to colleagues. Hellenophilia is a way of thought that allows those who look into the history of science to be blinded to science born in other cultures. Pingree states, in explanation of the term that "a Hellenophile suffers from a form of madness that blinds him or her to historical truth" He continues by explaining the main symptoms of Hellenophilia "the first of these is that the Greeks invented science; the second is that they discovered a way to truth, the scientific method, that we are now successfully following; the third is that the only real sciences are those that began in Greece; and the fourth (and last?) is that the true definition of science is just that which scientists happen to be doing now, following a method or methods adumbrated by the Greeks, but never fully understood or utilized by them". An anthropological etiology of Greek innovation in natural science is advanced by sociologist Michael G. Horowitz in "The Scientific Dialectic of Ancient Greece and the Cultural Tradition of Indo-European Speakers". Although Hellenophilia relates directly to


id: hidrodoe-20260505-0
file: data/en.wikipedia.org/wiki/Hidrodoe-0.md
category: reference
title: Hidrodoe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hidrodoe
date_saved: 2026-05-05T09:38:46.986766+00:00
instance: kb-cron
parent: hidrodoe-20260505-0
summary:
Hidrodoe is a science museum dedicated to water and located in the Netepark Herentals, Belgium. The central part of Hidrodoe consists of Waterworld where the visitor can have experiences and perform experiments with regard to water. The Waterworld itself comprises the Drop, the What Is Water Zone, the History Cave, the Landscape and the Aqua Station. == History == Hidrodoe was founded by Pidpa (Provinciale en Intercommunale Drinkwatermaatschappij van de Provincie Antwerpen) the water supply company of the Antwerp province. Hidrodoe was declared open to the public on the World Day for Water 2003. == Sources == Record aantal bezoekers voor Hidrodoe Archived 2011-06-12 at the Wayback Machine (Dutch) Hidrodoe (Pidpa) Hidrodoe (Flanders) == External links == Hidrodoe


id: historical-metrology-20260505-0
file: data/en.wikipedia.org/wiki/Historical_metrology-0.md
category: reference
title: Historical metrology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Historical_metrology
date_saved: 2026-05-05T09:38:48.236633+00:00
instance: kb-cron
parent: historical-metrology-20260505-0
summary:
Historical metrology is the science and study of the different units of measurement and measurement systems (including monetary units) which have been used by various countries and places throughout history. == Published reports == For some countries, principal divisions of executive governments have published reports that compile formerly used weights and measures. For example, this has been done for Bolivia, Great Britain, Costa Rica, Mexico, Portugal, Spain, Tanzania and the United States. In 1954, 1955, and 1966, the United Nations compiled reports aimed at giving an overview of the non-metric units then in use in different parts of the world. In 2018, the first of three volumes of the book "Encyclopaedia of Historical Metrology, Weights, and Measures" was published. The book addresses the myriad units of measurement that have arisen through the ages, from weights used by ancient cultures to the scientific units of the modern world. == See also == Dimensional metrology Forensic metrology Smart Metrology Time metrology Quantum metrology == References ==


id: homoeomeria-philosophy-20260505-0
file: data/en.wikipedia.org/wiki/Homoeomeria_(philosophy)-0.md
category: reference
title: Homoeomeria (philosophy)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Homoeomeria_(philosophy)
date_saved: 2026-05-05T09:38:49.459429+00:00
instance: kb-cron
parent: homoeomeria-philosophy-20260505-0
summary:
Homoeomeria was a doctrine in the philosophy of the ancient Greek Anaxagoras, as claimed by the Roman atomist Lucretius. It was assumed that the atoms constituting a substance must themselves have the salient observed properties of that substance: so atoms of water would be wet, atoms of iron would be hard, atoms of wool would be soft, etc. This doctrine depends on the fallacy of division. Professor Fleeming Jenkin wrote that: "we may with the exercise of a good deal of fancy see in the doctrine of homoeomeria, which taught that all things contained the materials of everything else in a latent state, a foreshadowing of the chemical theory which proves that our bodies are made of the same chemical materials as peas, cabbages, &c., but it requires an elastic imagination to link the old and new creed together." == References ==


id: international-scientific-committee-on-price-history-20260505-0
file: data/en.wikipedia.org/wiki/International_scientific_committee_on_price_history-0.md
category: reference
title: International scientific committee on price history
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/International_scientific_committee_on_price_history
date_saved: 2026-05-05T09:38:54.384134+00:00
instance: kb-cron
parent: international-scientific-committee-on-price-history-20260505-0
summary:
The International Scientific Committee on Price History was created in 1929 by William Beveridge and Edwin Francis Gay after receiving a five-year grant from the Rockefeller Foundation. The national representatives were William Beveridge for Great Britain, Moritz John Elsas for Germany, Edwin Francis Gay for the United States, Earl J. Hamilton for Spain, Henri Hauser for France and Alfred Francis Pribram for Austria; later, Franciszek Bujak for Poland and Nicolaas Wilhelmus Posthumus for the Netherlands also joined; Arthur H. Cole was in charge of finances for the whole project. == Books by the committee == Hamilton (Earl J.), American Treasure and the Price Revolution in Spain (1501–1650), 1934. Hamilton (Earl J.), Money, Prices and Wages in Valencia, Aragon and Navarre (1351–1500), 1936. Hauser (Henri), Recherches et documents sur l’histoire des prix en France de 1500 à 1800, 1936. Elsas (Moritz John), Umriß einer Geschichte der Preise und Löhne in Deutschland vom ausgehenden Mittelalter bis zum Beginn des 19. Jarhunderts, 3 vol., 1936–1949. Přibram (Alfred Francis), Materialien zur Geschichte der Preise und Löhne in Österreich, 1938. Cole (Arthur Harrison), Wholesale Commodity Prices in the United States 1700–1861, 1938. Beveridge (William H.), Prices and Wages in England from the 12th to the


id: ma-aseh-toviyyah-20260505-0
file: data/en.wikipedia.org/wiki/Ma'aseh_Toviyyah-0.md
category: reference
title: Ma'aseh Toviyyah
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ma'aseh_Toviyyah
date_saved: 2026-05-05T09:38:55.559739+00:00
instance: kb-cron
parent: ma-aseh-toviyyah-20260505-0
summary:
Ma'aseh Toviyyah or Ma'aseh Tobiyyah (Hebrew: מעשה טוביה, lit. 'Work of Tobias') was an encyclopedic scientific reference book written by Tobias Cohn. It was published in Venice, Italy, in 1707, and reprinted there in 1715, 1728, 1769, and 1850. == Contents == The work is divided into eight parts: (1) theology; (2) astronomy; (3) medicine; (4) hygiene; (5) Syphilitic maladies; (6) botany; (7) cosmography; and (8) an essay on the four elements. The most important is the third part, which contains an illustration showing a human body and a house side by side and comparing the members of the former to the parts of the latter (see illustration). == Illustrations and dictionary == In part 2 are found an astrolabe and illustrations of astronomical and mathematical instruments. Inserted between parts 6 and 7 is Turkish-Latin-Spanish dictionary; and prefixed to the work is a poem by Solomon Conegliano. == References == This article incorporates text from a publication now in the public domain: Singer, Isidore; et al., eds. (1901–1906). "Cohn, Tobias". The Jewish Encyclopedia. New York: Funk & Wagnalls.


id: ant-nio-de-mariz-carneiro-20260505-0
file: data/en.wikipedia.org/wiki/António_de_Mariz_Carneiro-0.md
category: reference
title: António de Mariz Carneiro
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/António_de_Mariz_Carneiro
date_saved: 2026-05-05T09:38:56.768451+00:00
instance: kb-cron
parent: ant-nio-de-mariz-carneiro-20260505-0
summary:
António de Mariz Carneiro (15?? in Lisbon – 1669) was a Portuguese nobleman who served as the official cosmographer to the Portuguese crown. == Biography == Mariz Carneiro was educated at the University of Osuna and the University of Coimbra, gaining a bachelor's degree in 1623. He came from the noble Mariz family, which had long been employed as judges and high officials at the Portuguese court. In 1631, Carneiro was appointed as Royal Cosmographer by Philip III of Portugal. This post had previously been occupied by Pedro Nunes. Mariz Carneiro published several books and was the first to include precise drawings, with coastal hydrology. Married first time with Angela de Menezes that died in 1642 in Porto, while he was nominated to be the judge of Porto court house. Married second time with his cousin Antonia Luisa de Menezes. == Works == Descrição da Fortaleza de Sofala e das mais da Índia (1639) Regimento de pilotos, e roteiro das navegaçoens da India Oriental : agora novamente emendado & acresentado co[m] o Roteiro da costa de Sofala, ate Mo[m]baça : & com os portos, & barras do Cabo de Finis taerra ate o Estreito de Gibaltar, com suas derrotas, sondas,


id: max-planck-institute-for-the-history-of-science-20260505-0
file: data/en.wikipedia.org/wiki/Max_Planck_Institute_for_the_History_of_Science-0.md
category: reference
title: Max Planck Institute for the History of Science
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Max_Planck_Institute_for_the_History_of_Science
date_saved: 2026-05-05T09:38:58.000797+00:00
instance: kb-cron
parent: max-planck-institute-for-the-history-of-science-20260505-0
summary:
The Max Planck Institute for the History of Science (German: Max-Planck-Institut für Wissenschaftsgeschichte) is a scientific research institute founded in March 1994. The Institute is one of the more than 80 research institutes of the Max Planck Society. Since its inception, the Institute has continually expanded the boundaries of the field of the history of science—critically interrogating basic concepts, bringing multiple disciplines into dialog, and experimenting with novel research methods.. == Organization and Research == The MPIWG comprises three departments and several independent research groups. As of August 2024, two departments are filled: "Knowledge Systems and Collective Life," directed by Etienne Benson "Artifacts, Action, Knowledge," directed by Dagmar Schäfer Hans-Jörg Rheinberger, who headed Department III from 1995 to 2014, and Lorraine Daston, who headed Department II from 1995 to 2019, remain at the MPIWG as emerita. Jürgen Renn headed the department "Structural Changes in Systems of Knowledge" from 1994 to 2023. The Research Groups are: "Astral Sciences in Trans-Regional Asia (ASTRA)," led by Anuj Misra. "China in the Global System of Science," led by Anna L. Ahlers "Experience in the Premodern Sciences of Soul & Body ca. 800–1650," led by Katja Krause The Institute also hosts an International Max Planck


id: molinology-20260505-0
file: data/en.wikipedia.org/wiki/Molinology-0.md
category: reference
title: Molinology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molinology
date_saved: 2026-05-05T09:38:59.199344+00:00
instance: kb-cron
parent: molinology-20260505-0
summary:
Molinology (from Latin: molīna, mill; and Greek λόγος, study) is the study of mills and other similar devices which use energy for mechanical purposes such as grinding, fulling or sawing. == Mill technology == The term "Molinology" was coined in 1965 by the Portuguese industrial historian João Miguel dos Santos Simões. Mills make use of moving water or wind, or the strength of animal or human muscle to power machines for purposes such as hammering, grinding, pumping, sawing, pressing or fulling. Since the material resources and technology available to harness mill power have varied across societies and across time, different human societies developed different solutions to the problem. Thus molinology is a multidisciplinary area of study which reaches beyond mechanical analysis of the mills. Cultural and scientific interest in molinology is maintained by The International Molinological Society (TIMS), a non-profit organisation which brings together around five hundred members worldwide. It was founded in 1973 after earlier international symposia in 1965 and 1969. The Society aims to retain the knowledge of those traditional engines which have been rendered obsolete by modern technical and economic trends. == See also == Watermill – Structure that uses a water wheel or turbine Tide mill


id: mus-um-d-histoire-naturelle-de-nice-20260505-0
file: data/en.wikipedia.org/wiki/Muséum_d'histoire_naturelle_de_Nice-0.md
category: reference
title: Muséum d'histoire naturelle de Nice
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Muséum_d'histoire_naturelle_de_Nice
date_saved: 2026-05-05T09:39:00.395015+00:00
instance: kb-cron
parent: mus-um-d-histoire-naturelle-de-nice-20260505-0
summary:
The Natural History Museum of Nice (French: Muséum d'histoire naturelle de Nice) is a French natural-history museum located in Nice. == Origins == The museum was founded in 1846 by Jean Baptiste Vérany (1800–1865), a French pharmacist and naturalist who specialized in the study of cephalopods, and Jean-Baptiste Barla (1817–1896), a French botanist. == Collections == It has extensive collections mainly from the Mediterranean region but also from Africa, the Indian Ocean and South America. Currently, following the upgrading of the exhibition halls, only the museum space built at the beginning of the 20th century is open to the public and constitutes the establishment's permanent exhibition hall. Periodically, a few temporary exhibitions are scheduled at Parc Phœnix, at the Louis-Nucéra library, at the Maison de la nature in the Grande Corniche departmental park. The museum was to be relocated to a future Cité des Sciences et de la Nature, including a new building for the museum and the Phoenix Park, with an opening scheduled for 2013. The project has been postponed indefinitely. == Location == The museum's address is 60 du boulevard Risso, just behind Place Garibaldi near the MAMAC (Musée d'Art Moderne et d'Art Contemporain), Nice, France. == See


id: nasa-historical-advisory-committee-20260505-0
file: data/en.wikipedia.org/wiki/NASA_Historical_Advisory_Committee-0.md
category: reference
title: NASA Historical Advisory Committee
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/NASA_Historical_Advisory_Committee
date_saved: 2026-05-05T09:39:01.614367+00:00
instance: kb-cron
parent: nasa-historical-advisory-committee-20260505-0
summary:
The National Aeronautics and Space Administration (NASA) Historical Advisory Committee was a committee of historians that was established in 1964. == History == The NASA Historical Office was established under its first chief historian, Dr. Eugene Emme in 1960. The committee was first made up of a wide variety of members, who initially sought to find support and prestige for the new historical program. From 1969 to 1970, the committee began to be increasingly composed of professional historians from universities, who made known their dissatisfaction with the NASA historical program. As a result, the Historical Advisory Committee was reduced in size and reorganized to be composed of only university-based professional historians to oversee the work of the NASA Historical Office. == Chairmen == Wood Gray, 1964-1966 Melvin Kranzeberg, 1966-1970 Louis Morton, 1970- Walter Rundell == Members == Daniel J. Boorstin David Bushnell James L. Cate, 1964- A. Hunter Dupree I. B. Holley Thomas P. Hughes Elting E. Morison, 1972- Robert P. Multhauf Rodman W. Paul Robert L. Perry John B. Rae == Sources == Rodman W. Paul, "Historical Advisory Committees: NASA and the National Archives," Pacific Historical Review, vol. 44, no. 3 (August 1975), pp. 385–394.


id: natural-magic-20260505-0
file: data/en.wikipedia.org/wiki/Natural_magic-0.md
category: reference
title: Natural magic
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural_magic
date_saved: 2026-05-05T09:39:03.992122+00:00
instance: kb-cron
parent: natural-magic-20260505-0
summary:
Natural magic is a tradition concerning the manipulation and development of the occult, or hidden, mechanisms within nature. Unlike ceremonial magic, it does not rely on a relationship with summoning spirits. Natural magic sometimes makes use of physical substances from the natural world such as stones or herbs. In the Medieval era, many theologians utilized the term natural magic when referring to the properties of the natural world that would operate within the realm of divinity. Natural magic worked to expose underlying mechanisms occurring in nature that cannot be explained through rational knowledge. The lack of concrete evidence results in these mechanisms being referred to as "occult properties". Natural magic so defined includes astrology, alchemy, and certain disciplines that would today be considered fields of natural science, such as astronomy and chemistry (divergently evolved from astrology and alchemy, respectively) or botany (from herbology). Jesuit scholar Athanasius Kircher wrote that "there are as many types of natural magic as there are subjects of applied sciences". Heinrich Cornelius Agrippa discusses natural magic in his Three Books of Occult Philosophy (1533), where he calls it "nothing else but the highest power of natural sciences". The Italian Renaissance philosopher Giovanni Pico della Mirandola, who


id: natural-magic-20260505-1
file: data/en.wikipedia.org/wiki/Natural_magic-1.md
category: reference
title: Natural magic
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural_magic
date_saved: 2026-05-05T09:39:03.992122+00:00
instance: kb-cron
parent: natural-magic-20260505-0
summary:
During the Scientific Revolution in the seventeenth century, the way science was viewed started to drastically change. The role of natural magic began to shift, but it did not disappear. Specifically, the idea of “occult properties” had an important role in the developing scientific worldview. The invisible forces in nature, which were previously thought of as magical concepts, came to be known as more rational and mathematical ones. For example, phenomena such as gravity and light were once thought to be mysterious, unknown forces, but during the Scientific Revolution, scientists began to explain them as rays or forces acting across a space. This transformation of thought is shown through figures like Isaac Newton, whose theory of gravity relied on a force at a distance, similar to earlier beliefs related to natural magic. While Newton and other scientists moved away from magical explanations, theories of natural magic helped to inspire their work. Despite beliefs and reasonings changing, “occult qualities” helped to establish ideas such as force interactions, which remain a central part of modern physics today. == See also == Kitāb al-nawāmīs – Arabic book of magic Giambattista della Porta – Italian polymath (1535–1615) Magia Naturalis – Book by Giambattista della


id: neeff-s-wheel-20260505-0
file: data/en.wikipedia.org/wiki/Neeff's_wheel-0.md
category: reference
title: Neeff's wheel
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Neeff's_wheel
date_saved: 2026-05-05T09:39:06.522988+00:00
instance: kb-cron
parent: neeff-s-wheel-20260505-0
summary:
Neeff's wheel, also known as the Blitzrad (German: "lightning wheel" or "spark wheel") is a historical electrical apparatus. It is a kind of contact breaker, designed to interrupt an electrical circuit at periodic intervals, producing visible sparks. It was first presented in the 1830s by the German scientist Christian Ernst Neeff (1782–1849). The arrangement consists of a toothed wheel against which a conductive wire is pressed (by a spring something like that of a mousetrap). Electrical current flows through the wheel into the wire. When the gear wheel is turned, each tooth of the gear causes the wire to ride up and then briefly drop down, losing contact with the wheel and generating a spark. The gear wheel can be driven by a hand crank. Instead of air, the gaps between the teeth of the gear wheel may be filled with a solid electrical insulator such as ebony wood. Neeff credited this innovation to his colleague Johann Philipp Wagner. Neeff's wheel was a forerunner of the modern contact breaker. == References ==


id: oil-of-brick-20260505-0
file: data/en.wikipedia.org/wiki/Oil_of_brick-0.md
category: reference
title: Oil of brick
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_of_brick
date_saved: 2026-05-05T09:39:07.683020+00:00
instance: kb-cron
parent: oil-of-brick-20260505-0
summary:
Oil of brick, called by apothecaries Oleum de Lateribus and by alchemists Oil of Philosophers, was an empyreumatic oil obtained by subjecting a brick soaked in oil, such as olive oil, to distillation at a high temperature. == Manufacture == The process initially started with pieces of brick, which were heated red hot in live coals, and extinguished in an earth half-saturated with olive oil. Being then separated and pounded grossly, the brick absorbs the oil. It was then put in a retort, and placed in a reverberatory furnace, where the oil was drawn out by fire. == Uses == Oil of brick was used in pre-modern medicine as a treatment for tumors, in the spleen, in palsies, and epilepsies. It was used by lapidaries as a vehicle for the emery by which stones and gems were sawn or cut. == References ==


id: oman-children-s-museum-20260505-0
file: data/en.wikipedia.org/wiki/Oman_Children's_Museum-0.md
category: reference
title: Oman Children's Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oman_Children's_Museum
date_saved: 2026-05-05T09:39:08.893004+00:00
instance: kb-cron
parent: oman-children-s-museum-20260505-0
summary:
The Oman Children's Museum is a children's science museum, located near Qurum Nature Park off Sultan Qaboos Street in a white-domed building in Muscat, Oman. The museum was established by the Ministry of National Heritage and Culture and opened on November 17, 1990, by Sultan Qaboos bin Said al Said on the 20th National Day celebration in Oman. The museum has 45 exhibits and two demonstrations and comprises 10,000 square feet (930 m2). It was the first science museum in Oman and is visited by around 50,000 visitors annually. The museum is currently run by a former school teacher, Samirah Ahmed al Raisi, who has run the museum for over six years. The museum addresses the scientific ways of human life and the exhibition section is divided into three parts; The Human life, Physics and observation which investigates the progression of science through the ages. The museum has many hands-on displays. These include experiences of a fake electric shock, trigger a lightning bolt, launching a hot air balloon, photographing your own shadow, and sending message through a whisper dish. == See also == List of museums in Oman == References ==


id: optical-square-20260505-0
file: data/en.wikipedia.org/wiki/Optical_square-0.md
category: reference
title: Optical square
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_square
date_saved: 2026-05-05T09:39:10.158697+00:00
instance: kb-cron
parent: optical-square-20260505-0
summary:
The optical square uses a pentaprism to reflect and refract a beam or sighting 90 degrees, it is used in pairs in surveying and in a singular block in metrology. In optical square A Horizon glass is placed at an angle of 120° with the horizon sight. The Index glass is placed at an angle of 105° with the Index sight. Angle between Index glass and Horizon glass is 45°. == Metrology == Used with an autocollimator or angle dekkor and mirror it can be used for machine tool axis squareness checking and for measuring the squareness of surfaces. It has two mirrors at 45 degree to each other. One is half-silvered, called horizon glass, and other is fully silvered, called index glass. It measures angle by double reflection. Two prisms can be used as an optical square. == Optical square in surveying == In surveying it is used both as a hand held tool for sighting between two poles (often with a plumb bob hung from the handle) and also mounted on a Jacob's staff. == References ==


id: abraham-pais-prize-20260505-0
file: data/en.wikipedia.org/wiki/Abraham_Pais_Prize-0.md
category: reference
title: Abraham Pais Prize
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abraham_Pais_Prize
date_saved: 2026-05-05T09:39:11.449917+00:00
instance: kb-cron
parent: abraham-pais-prize-20260505-0
summary:
The Abraham Pais Prize for History of Physics is an award given each year since 2005 jointly by the American Physical Society and the American Institute of Physics for "outstanding scholarly achievements in the history of physics". The prize is named after Abraham Pais (1918–2000), science historian and particle physicist; as of 2024 the recipient receives US$10,000 and a certificate citing the contributions of the recipient, plus an allowance for travel to an APS meeting to receive the award and deliver a lecture on the history of physics. == Recipients == Source: == See also == List of American Physical Society prizes and awards List of physics awards == External links == Abraham Pais Prize for History of Physics, American Physical Society == References ==


id: mus-e-pasteur-20260505-0
file: data/en.wikipedia.org/wiki/Musée_Pasteur-0.md
category: reference
title: Musée Pasteur
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Musée_Pasteur
date_saved: 2026-05-05T09:39:12.656578+00:00
instance: kb-cron
parent: mus-e-pasteur-20260505-0
summary:
The Musée Pasteur (French pronunciation: [myze pastœʁ], lit. 'Pasteur Museum') is a museum dedicated to French scientist Louis Pasteur. It is located within the Institut Pasteur at 25 Rue du Docteur Roux, Paris, France, in the 15th arrondissement, and is open daily in the warmer months; an admission fee is charged. The museum was established in 1935, in honor of Louis Pasteur, and preserves his memory in the apartment where he spent the last seven years of his life, it also has an impressive room where some 1,000 scientific instruments are exhibited. The museum houses the Neo-Byzantine chapel in which he is buried. The building was classified as a historical monument in 1981. == See also == List of museums in Paris List of things named after Louis Pasteur == References == Musée Pasteur Pariserve description (French) Stephen Fallon, Paris, Lonely Planet, 2004, page 109. ISBN 1-74059-760-5.


id: petrosains-20260505-0
file: data/en.wikipedia.org/wiki/Petrosains-0.md
category: reference
title: Petrosains
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Petrosains
date_saved: 2026-05-05T09:39:13.937666+00:00
instance: kb-cron
parent: petrosains-20260505-0
summary:
Petrosains, also known as Petrosains, The Discovery Centre is a Malaysian science and technology museum located in the heart of Kuala Lumpur within Suria KLCC, Petronas Twin Towers. Petrosains was a brainchild of 4th Prime Minister Mahathir Mohamad and established on 25 March 1999. It is owned and operated by Petrosains Sdn. Bhd., a wholly owned subsidiary of the Malaysian oil and gas conglomerate Petronas. Tengku Nasariah Tengku Syed Ibrahim is the CEO of Petrosains until 2018. The current CEO is Ezarisma Azni Mohamad. Petrosains also a principal organizer of the annual Petrosains Science Festival since its inauguration in 2013. Since its establishment in 1999, Petrosains' primary language has been always English, which was used in all of its daily operations and official matters instead of Malay. However, most of programs held in Petrosains are still conducted in Malay. == Galleries == Among galleries available at Petrosains are: Dark Ride Space Speed Molecule Nano World 3D Theatre == Operating Hours == Weekdays: 9:30 a.m. - 5:30 p.m. (Last admission 4:00 p.m.) Weekdays and Public Holidays: 9:30 a.m. - 6:30 p.m. (Last admission 5:00 p.m.) Closed On The First Monday of The Month == Admission Rates == === Optional Admissions ===


id: pharmacy-museum-of-the-jagiellonian-university-medical-college-20260505-0
file: data/en.wikipedia.org/wiki/Pharmacy_Museum_of_the_Jagiellonian_University_Medical_College-0.md
category: reference
title: Pharmacy Museum of the Jagiellonian University Medical College
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pharmacy_Museum_of_the_Jagiellonian_University_Medical_College
date_saved: 2026-05-05T09:39:15.106992+00:00
instance: kb-cron
parent: pharmacy-museum-of-the-jagiellonian-university-medical-college-20260505-0
summary:
Muzeum Farmacji Collegium Medicum Uniwersytetu Jagiellońskiego (Pharmacy Museum, Jagiellonian University Medical College) is a museum on Floriańska Street, Kraków, Poland, specializing in the history of pharmacy and pharmaceutical technology. It was established in 1946. The museum was founded by Stanisław Proń, legal counsel and administrative director of the Regional Chamber of Pharmacists in Kraków. Until the late 1980s, the museum was housed in the building at 3 ul. Basztowa. It was then transferred to the newly renovated building at ul. St. Florian's, where it remains today. It is the largest and oldest Museum of Pharmacy in Poland, and one of the largest museums of its kind in the world. The museum occupies all five floors of the building, including the basement and the attic, in a manner appropriate to the historical use of such premises in as an apothecary. On the first floor is a room dedicated to Ignacy Łukasiewicz, a pharmacist, pioneer in the field of crude oil, and the inventor of the modern kerosene lamp. The room on the second floor of the exhibition is devoted to Tadeusz Pankiewicz, a Roman Catholic who ran the "Under the Eagle" pharmacy in the Kraków Ghetto during the Nazi occupation of


id: post-office-box-electricity-20260505-0
file: data/en.wikipedia.org/wiki/Post_office_box_(electricity)-0.md
category: reference
title: Post office box (electricity)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Post_office_box_(electricity)
date_saved: 2026-05-05T09:39:16.280999+00:00
instance: kb-cron
parent: post-office-box-electricity-20260505-0
summary:
The post office box was a Wheatstone bridge–style testing device with pegs and spring arms to close electrical circuits and measure properties of the circuit under test. == Resistance measurement == The boxes were used in the United Kingdom by engineers from then General Post Office, who were responsible for UK telecommunications to trace electrical faults, i.e. to determine where a break occurred in a cable which could be several miles in length. It works on the principle of Wheatstone bridge to identify the resistance of wire connected and then by using wire resistivity and cross section calculating length of wire and thus determining where the cable had broken. Post office boxes were common pieces of scientific apparatus in the UK O-Level and A-Level schools public examination physics syllabus in the 1960s. == Construction == A typical post office box is in a wooden box with a hinged lid and a metal or bakelite panel showing circuit connections. Coils of wire are wound non-inductively, mounted in the body of the box, and have a negligible temperature coefficient. Pairs of ratio arms are each 5 10 20 ohms. Resistance arms contains a number of coils from 1 to 5000 ohms with


id: la-recherche-expedition-20260505-0
file: data/en.wikipedia.org/wiki/La_Recherche_Expedition-0.md
category: reference
title: La Recherche Expedition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/La_Recherche_Expedition
date_saved: 2026-05-05T09:39:17.456269+00:00
instance: kb-cron
parent: la-recherche-expedition-20260505-0
summary:
The La Recherche Expedition of 1838 to 1840 was a French Admiralty expedition whose destination was the North Atlantic and Scandinavian islands, including the Faroe Islands, Spitsbergen and Iceland. The expedition in the Scandinavian countries from 1838 to 1840, was a direct continuation of shipments in 1835 and 1836. A letter dated 22 March 1837 revealed that Joseph Paul Gaimard and Xavier Marmier were preparing a trip to Copenhagen and Christiania (Norway) whose purpose was to gather additional information on Iceland and Greenland. On 13 June 1838 the French corvette La Recherche left Le Havre in France, bound for Northern Scandinavia. Joseph Paul Gaimard (1796–1858), a physician and zoologist was the commanding officer of the expedition. The expedition was on a purely scientific nature, rather than a colonial venture in cooperation with the governments of Norway and Sweden. Gaimard invited the Sámi minister and botanist Lars Levi Læstadius on the voyage for his knowledge in botany and Sámi culture. Auguste Bravais, a French scientist and Louis Bévalet, a French artist, also accompanied the expedition. The company was given an international dimension. Gaimard had hired many renowned European scholars. The Arctic exploration in the 1870s marked a watershed in the history


id: repeating-circle-20260505-0
file: data/en.wikipedia.org/wiki/Repeating_circle-0.md
category: reference
title: Repeating circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Repeating_circle
date_saved: 2026-05-05T09:39:18.640518+00:00
instance: kb-cron
parent: repeating-circle-20260505-0
summary:
The repeating circle is an instrument for geodetic surveying, developed from the reflecting circle by Étienne Lenoir in 1784. He invented it while an assistant of Jean-Charles de Borda, who later improved the instrument. It was notable as being the equal of the great theodolite created by the renowned instrument maker, Jesse Ramsden. It was used to measure the meridian arc from Dunkirk to Barcelona by Jean Baptiste Delambre and Pierre Méchain (see: meridian arc of Delambre and Méchain). == Construction and operation == The repeating circle is made of two telescopes mounted on a shared axis with scales to measure the angle between the two. The instrument combines multiple measurements to increase accuracy with the following procedure: At this stage, the angle on the instrument is double the angle of interest between the points. Repeating the procedure causes the instrument to show 4× the angle of interest, with further iterations increasing it to 6×, 8×, and so on. In this way, many measurements can be added together, allowing some of the random measurement errors to cancel out. == Use in geodetic surveys == The repeating circle was used by César-François Cassini de Thury, assisted by Pierre Méchain, for the


id: rescuing-prometheus-20260505-0
file: data/en.wikipedia.org/wiki/Rescuing_Prometheus-0.md
category: reference
title: Rescuing Prometheus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rescuing_Prometheus
date_saved: 2026-05-05T09:39:19.846216+00:00
instance: kb-cron
parent: rescuing-prometheus-20260505-0
summary:
Rescuing Prometheus: Four Monumental Projects That Changed the Modern World (1998) is a book by Thomas P. Hughes. The book uses four extremely large engineering projects of the late 20th century as examples to explore how the limits of modern system engineering are stressed by real life projects. It also traces the development of the management of large technical system development. The book documents four massively-cooperative projects: Semi-Automatic Ground Environment (SAGE), a computer- and radar-based air-defense system The Atlas project, which produced America's first ICBM Boston's Central Artery/Tunnel Project, a traffic-unclogging system of highways, tunnels and bridges originally scheduled for completion in 2004 ARPANET, an interactive computer-based information network that paved the way for the Internet == See also == Large Technical System == References == Rescuing Prometheus: Four Monumental Projects That Changed the Modern World (ISBN 0-679-73938-6) by Thomas P. Hughes, 2000.


id: rhetorius-20260505-0
file: data/en.wikipedia.org/wiki/Rhetorius-0.md
category: reference
title: Rhetorius
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rhetorius
date_saved: 2026-05-05T09:39:21.032525+00:00
instance: kb-cron
parent: rhetorius-20260505-0
summary:
Rhetorius of Egypt (Greek: Ῥητόριος) was the last major classical astrologer from whom we have any excerpts. He lived in the sixth or early seventh century, in the early Byzantine era. He wrote an extensive compendium in Greek of the techniques of the Hellenistic astrologers who preceded him, and is one of our best sources for the work of Antiochus of Athens. Although no intact original manuscript survives of his work, we do have several late Byzantine versions of it. Rhetorius provides important confirmation of the survival of the more obscure astrological techniques of Vettius Valens, the practicing astrologer whose tradition is somewhat at variance with the more well-known methods of Claudius Ptolemy; for example, in his treatment of the Lot of Fortune as a horoskopos, much as Valens treated Lots, and in his use of sect with lots. In addition, Rhetorius discusses the late-Roman systems of time lords, a topic which came to be heavily developed by the Persians, Arabs and medieval Europeans. Rhetorius provides an informative link between the earlier Hellenistic tradition and the Arab and medieval practices that followed him. == Sources == Rhetorius qui dictur: Compendium astrologicum: Libri Vi et VI, edited by David Pingree, Berlin,


id: robert-of-chester-20260505-0
file: data/en.wikipedia.org/wiki/Robert_of_Chester-0.md
category: reference
title: Robert of Chester
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Robert_of_Chester
date_saved: 2026-05-05T09:39:22.215028+00:00
instance: kb-cron
parent: robert-of-chester-20260505-0
summary:
Robert of Chester (Latin: Robertus Castrensis) was an English Arabist of the 12th century. He translated several historically important books from Arabic to Latin, such as: Book on the Composition of Alchemy (Liber de compositione alchemiae): translated in 1144, this was the first book on alchemy to become available in Europe Compendious Book on Calculation by Completion and Balancing (Liber algebrae et almucabola): al-Khwārizmī's book about algebra, translated in 1145 In the 1140s Robert worked in Iberia, where the division of the region between Muslim and Christian rulers resulted in opportunities for interchange between the different cultures. However, by the end of the decade he had returned to England. Some sources identify him with Robert of Ketton (Latin: Robertus Ketenensis) who was also active as an Arabic-Latin translator in the 1140s. However, Ketton and Chester, while both places in England, are a long way apart. Also, when in Iberia, Robert of Ketton was based in the Kingdom of Navarre, whereas Robert of Chester is known to have worked in Segovia. == See also == Latin translations of the 12th century Louis Charles Karpinski == Notes == == References == Lo Bello, Anthony (22 April 2024). "Robert of Chester". The commentary


id: george-n-saegmuller-20260505-0
file: data/en.wikipedia.org/wiki/George_N._Saegmuller-0.md
category: reference
title: George N. Saegmuller
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/George_N._Saegmuller
date_saved: 2026-05-05T09:39:23.402663+00:00
instance: kb-cron
parent: george-n-saegmuller-20260505-0
summary:
George N. Saegmuller (1847 - 1934) was an American inventor of many astronomical instruments and other mechanical devices. == Early life == Saegmuller attended technical schools in Erlangen and Nuremberg. In 1870 he moved to the United States, where he settled in Washington, D.C., and began working for a craftsman involved in the production of astronomical and geodetic instruments. He also worked for the United States Coast and Geodetic Survey in charge of precision instruments. == Personal life == Saegmuller married Maria Jane Van den Bergh while living in Washington and lived on the Van den Bergh family farm, Reserve Hill, in Arlington County, Virginia. Saegmuller was involved in many different scientific pursuits including road maintenance and water wheel pumps. He worked with Camill Fauth in the scientific equipment supply business. == Career == Saegmuller invented or contributed to the development of a multitude of devices. He held more than 35 patents. His inventions include the solar attachment for engineering transits, a new type of naval bore sight, and numerous telescopes and telescope mounts. Saegmuller, as part of Fauth & Co., joined with Bausch & Lomb Optical Company in 1905. == Death == He died on February 12, 1934, in


id: shapur-ibn-sahl-20260505-0
file: data/en.wikipedia.org/wiki/Shapur_ibn_Sahl-0.md
category: reference
title: Shapur ibn Sahl
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Shapur_ibn_Sahl
date_saved: 2026-05-05T09:39:24.561699+00:00
instance: kb-cron
parent: shapur-ibn-sahl-20260505-0
summary:
Sābūr ibn Sahl (شاپور بن سهل گندیشاپوری; d. 869 CE) was a 9th-century Persian Christian physician from the Academy of Gundishapur. Among other medical works, he wrote one of the first medical books on antidotes called Aqrabadhin (القراباذين), which was divided into 22 volumes, and which was possibly the earliest of its kind to influence Islamic medicine. This antidotary enjoyed much popularity until it was superseded Ibn al-Tilmidh's version later in the first half of twelfth century. == See also == List of Iranian scientists == References == == Further reading == F. Wustenfled: arabische Aerzte (25, 1840).


id: small-science-20260505-0
file: data/en.wikipedia.org/wiki/Small_science-0.md
category: reference
title: Small science
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Small_science
date_saved: 2026-05-05T09:39:25.807361+00:00
instance: kb-cron
parent: small-science-20260505-0
summary:
Small science (in contrast to big science) is science performed in a smaller scale, such as by individuals, small teams or within community projects. Bodies which fund research, such as the National Science Foundation, DARPA, and the EU with its Framework programs, have a tendency to fund larger-scale research projects. Reasons include the idea that ambitious research needs significant resources devoted for its execution and the reduction of administrative and overhead costs on the funding body side. However, small science which has data that is often local and is not easily shared is funded in many areas such as chemistry and biology by these funding bodies. == Importance == Small Science helps define the goals and directions of large scale scientific projects. In turn, results of large scale projects are often best synthesized and interpreted by the long-term efforts of the Small Science community. In addition, because Small Science is typically done at universities, it provides students and young researchers with an integral involvement in defining and solving scientific problems. Hence, small science can be seen as an important factor for bringing together science and society. According to the Chronicle for Higher Education, James M. Caruthers, a professor of chemical


id: sodalitas-litterarum-vistulana-20260505-0
file: data/en.wikipedia.org/wiki/Sodalitas_Litterarum_Vistulana-0.md
category: reference
title: Sodalitas Litterarum Vistulana
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Sodalitas_Litterarum_Vistulana
date_saved: 2026-05-05T09:39:27.009350+00:00
instance: kb-cron
parent: sodalitas-litterarum-vistulana-20260505-0
summary:
Sodalitas Litterarum Vistulana ("Literary Sodality of the Vistula") was an international academic society modelled after the Roman Academy, founded circa 1495 in Kraków by Conrad Celtes, a German humanist scholar who also founded the Sodalitas Literarum Hungarorum in Hungary and the Sodalitas Literarum Rhenana (of the Rhine) in Heidelberg. In 1494, the seat was transferred from Cracow to Vienna and the name was changed to Sodalitas Litterarum Danubiana (of the Danube). Between 1497 and 1499, it was presided by the John Vitéz the Younger (died 1499) bishop of Vienna, nephew of John Vitéz. Notable members, besides Celtes, were Johann Reuchlin, Johannes Trithemius, Jakob Wimpfeling, Conrad of Leonberg, Johannes Cuspinian, and Filippo Buonaccorsi, Laurentius Corvinus and Johann Sommerfeld the Elder (died 1501). == References ==


id: michael-sokal-20260505-0
file: data/en.wikipedia.org/wiki/Michael_Sokal-0.md
category: reference
title: Michael Sokal
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Michael_Sokal
date_saved: 2026-05-05T09:39:28.168762+00:00
instance: kb-cron
parent: michael-sokal-20260505-0
summary:
Michael Mark Sokal was an American historian and educator. He died on Dec 18, 2025, age 80 . Born in Brooklyn, New York, on October 6, 1945, he was the son of the late Martin and Adele (Wattenberg) Sokal. After earning a degree in engineering and a doctorate in history, he joined the History faculty at Worcester Polytechnic Institute and published many works exploring the history of science, technology, and psychology. He also served as an editor and administrator for several prominent national organizations, including the History of Science Society, American Psychological Association, National Endowment for the Humanities, and National Science Foundation. He taught his entire career at Worcester Polytechnic Institute in the history of science. He received his PhD in history of science and technology from Case Western Reserve University in 1972. His research focused on James McKeen Cattell, a prominent psychologist and scientific impresario in the late 19th and early 20th centuries. He was the 2004-2005 president of the History of Science Society. == References ==


id: stratonautical-space-suit-20260505-0
file: data/en.wikipedia.org/wiki/Stratonautical_space_suit-0.md
category: reference
title: Stratonautical space suit
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Stratonautical_space_suit
date_saved: 2026-05-05T09:39:29.332038+00:00
instance: kb-cron
parent: stratonautical-space-suit-20260505-0
summary:
The stratonautical space suit (Spanish: escafandra estratonáutica) was a pressurised suit designed by Colonel Emilio Herrera in 1935 to be worn during a stratospheric flight using an open-basket balloon scheduled for the following year. It is considered one of the antecedents of the space suit. The flight never took place, due to the start of the Spanish Civil War. Herrera, a supporter of the Republican side, fled in 1939 to France, where he died in exile in 1967. The balloon, made of vulcanized silk, was cut and used to make raincoats for the troops. The suit was in the Cuatro Vientos airbase, fell to the Nationalist side and disappeared. It would have been the first fully pressurized functional suit in history, although it was never worn under real conditions. The suit had a woolen layer and a hermetic cover on the inside (tested in the bathroom of Herrera's apartment in Seville), covered with an articulated metal frame with accordion-like folds. It had articulated parts for the shoulders, hips, elbows, knees, and fingers. The mobility of the suit was tested at the Cuatro Vientos experimental station, and according to Herrera it was "satisfactory". The suit was supplied with pure oxygen. Herrera


id: takwin-20260505-0
file: data/en.wikipedia.org/wiki/Takwin-0.md
category: reference
title: Takwin
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Takwin
date_saved: 2026-05-05T09:39:30.520733+00:00
instance: kb-cron
parent: takwin-20260505-0
summary:
Takwin (Arabic: تكوين, lit. 'creation') was a goal of certain Muslim alchemists, notably Jabir ibn Hayyan. In the alchemical context, takwin refers to the creation of synthetic life in the laboratory, up to and including human life. Whether Jabir meant this goal to be interpreted literally is unknown. Jabir states in his Book of Stones (4:12) that "The purpose is to baffle and lead into error everyone except those whom God loves and provides for!" The Book of Stones was deliberately written in a highly esoteric code, so that only those who had been initiated into his alchemical school could understand them. It is therefore difficult at best for the modern reader to discern which aspects of Jabir's work are to be read as symbols (and what those symbols mean), and what is to be taken literally. Kathleen Malone O'Connor writes: From the emic perspective of the alchemist, the act of takwin was an emulation of the divine creative and life-giving powers of Genesis and Resurrection and tapped the physical and spiritual forces in nature. At the same time it was an act through which the alchemist was inwardly transformed and purified, a spiritual regeneration. Such an act highlights the


id: technopolis-belgium-20260505-0
file: data/en.wikipedia.org/wiki/Technopolis_(Belgium)-0.md
category: reference
title: Technopolis (Belgium)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Technopolis_(Belgium)
date_saved: 2026-05-05T09:39:31.741567+00:00
instance: kb-cron
parent: technopolis-belgium-20260505-0
summary:
Technopolis is a Flemish technology education centre located in Mechelen. == Flanders Technology International == Technopolis is an initiative which grew out of the Flanders Technology International (FTI) Foundation, which was an initiative of the Flemish government. Since 7 October 1999, the FTI offices are located within the premises of the Technopolis centre and the name of the organization was changed to Technopolis. The goal of the organization is to stimulate biotechnology and micro-electronics, and to increase the visibility of science in Flanders. == Exhibition == The Technopolis science museum was opened on 26 February 2000. It has a permanent interactive (hands-on) exhibition for science and technology on display. == See also == Science and technology in Flanders Agoria, technology industry in Belgium. Institute for the promotion of Innovation by Science and Technology (IWT) Interuniversity Microelectronics Centre (IMEC) Deutsches Museum Euro Space Center Evoluon Scienceworks Museum Telus Spark == External links == Technopolis


id: thermo-galvanometer-20260505-0
file: data/en.wikipedia.org/wiki/Thermo_galvanometer-0.md
category: reference
title: Thermo galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermo_galvanometer
date_saved: 2026-05-05T09:39:32.932584+00:00
instance: kb-cron
parent: thermo-galvanometer-20260505-0
summary:
The thermo-galvanometer is an instrument for measuring small electric currents. It was invented by William Duddell about 1900. The following is a description of the instrument taken from a trade catalog of Cambridge Scientific Instrument Company dated 1905: For a long time the need of an instrument capable of accurately measuring small alternating currents has been keenly felt. The high resistance and self-induction of the coils of instruments of the electro-magnetic type frequently prevent their use. Electro-static instruments as at present constructed are not altogether suitable for measuring very small currents, unless a sufficient potential difference is available. The thermo-galvanometer designed by Mr W. Duddell can be used for the measurement of extremely small currents to a high degree of accuracy. It has practically no self-induction or capacity and can therefore be used on a circuit of any frequency (even up to 120,000~ per sec.) and currents as small as twenty micro-amperes can be readily measured by it . It is equally correct on continuous and alternating currents. It can therefore be accurately standardized by continuous current and used without error on circuits of any frequency or wave-form. The principle of the thermo-galvanometer is simple. The instrument consists of a


id: tinamou-egg-20260505-0
file: data/en.wikipedia.org/wiki/Tinamou_egg-0.md
category: reference
title: Tinamou egg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tinamou_egg
date_saved: 2026-05-05T09:39:47.762183+00:00
instance: kb-cron
parent: tinamou-egg-20260505-0
summary:
The tinamou egg in Darwin's collection is an egg from the spotted nothura, and is the only specimen left in Darwin's collections during his HMS Beagle voyage. The egg has a large crack because Darwin put it in a box too small for it. It was rediscovered by volunteer Liz Wetton in February 2009, the 200th year of Darwin's birth, while she was sorting the egg collection in the zoology museum at the University of Cambridge. == References ==


id: vedic-science-20260505-0
file: data/en.wikipedia.org/wiki/Vedic_science-0.md
category: reference
title: Vedic science
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Vedic_science
date_saved: 2026-05-05T09:39:48.966221+00:00
instance: kb-cron
parent: vedic-science-20260505-0
summary:
Vedic science refers to a pseudoscientific system of knowledge based on the Vedas, a large body of religious texts originating in ancient India. == See also == Ayurveda Hindu cosmology Hindu views on evolution Indian mathematics Indian units of measurement Science and technology in ancient India Shastra Vimana == References ==


id: westphal-balance-20260505-0
file: data/en.wikipedia.org/wiki/Westphal_balance-0.md
category: reference
title: Westphal balance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Westphal_balance
date_saved: 2026-05-05T09:39:50.171625+00:00
instance: kb-cron
parent: westphal-balance-20260505-0
summary:
A Westphal balance (also known as a Mohr balance) is a scientific instrument used to measure the density of liquids. == References ==


id: yuasa-phenomenon-20260505-0
file: data/en.wikipedia.org/wiki/Yuasa_Phenomenon-0.md
category: reference
title: Yuasa Phenomenon
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Yuasa_Phenomenon
date_saved: 2026-05-05T09:39:51.411882+00:00
instance: kb-cron
parent: yuasa-phenomenon-20260505-0
summary:
The Yuasa Phenomenon, named after Japanese physicist and science historian Mitsutomo Yuasa (sometimes referred to as Mintomo Yuasa), suggests that, in the modern era, the world center of scientific activity (defined as producing more than 25% of the world's scientific achievements) moves from one country to another about every 80–100 years. == Analysis == Analyzed data indicate that the "modern world science centre has shifted from Italy (1504–1610) to the United Kingdom (1660–1750), to France (1760– 1840), to Germany (1875–1920), and to the United States (1920 to the present)." This phenomenon and its study methodology are an emerging scientometrics study area. Indicators point to China's rise as a world center of scientific activity. This phenomenon is also described by other names, including "the Bernal—Yuasa phenomenon". Shigeo Minowa links Yuasa's finding to Joseph Ben-David's movements of Centers of Learning. Ben-David's Centers of Learning migration observations are discussed in various works. == See also == Historic recurrence History of science == References ==


id: zurich-notebook-20260505-0
file: data/en.wikipedia.org/wiki/Zurich_Notebook-0.md
category: reference
title: Zurich Notebook
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Zurich_Notebook
date_saved: 2026-05-05T09:39:52.569701+00:00
instance: kb-cron
parent: zurich-notebook-20260505-0
summary:
The Zurich Notebook is one of Albert Einstein's notebooks, from his time in Zürich. It contains much of Einstein's foundational work on general relativity. == References ==


id: list-of-astronomical-instruments-20260505-0
file: data/en.wikipedia.org/wiki/List_of_astronomical_instruments-0.md
category: reference
title: List of astronomical instruments
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_astronomical_instruments
date_saved: 2026-05-05T09:39:54.131182+00:00
instance: kb-cron
parent: list-of-astronomical-instruments-20260505-0
summary:
An astronomical instrument is a device for observing, measuring or recording astronomical data. They are used in the scientific field of astronomy, a natural science that studies celestial objects and the phenomena that occur in the cosmos, with the object of explaining their origin and evolution over time. Many are also used in navigation and surveying. Astronomical instruments include: == See also == Astronomy Outline of astronomy Surveying instrument Measurement instrument == Notes ==


id: active-surface-20260505-0
file: data/en.wikipedia.org/wiki/Active_surface-0.md
category: reference
title: Active surface
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Active_surface
date_saved: 2026-05-05T09:39:55.307901+00:00
instance: kb-cron
parent: active-surface-20260505-0
summary:
An active surface is a surface of a radio telescope that is under active computer control of its shape. Large radio telescopes (more than 10 m in diameter or length) always bend during operation, due to their enormous weight and the fact that even the strongest materials are not perfectly stiff. This bending, in the range of a few millimetres, does not affect low frequency operation much, but dramatically reduces the efficiency of the telescope at higher frequencies where the wavelengths are comparable to the distortion. Typically, the efficiency of a telescope drops appreciably when the deviation from the desired shape is more than 1/10 of the considered wavelength. An active surface uses numerous small actuators to move the surface panels with respect to the underlying frame, and thus maintain the correct shape. An active surface can try to compensate for many different types of errors. The first is gravity—this is simplest since previous measurements, or even a mathematical model, can be used to predict (and correct) any bending. More difficult is correction for wind and thermal errors, since these require measuring and correcting in real time. Some examples of active surfaces are: Green Bank Telescope Large Millimeter Telescope Sardinia


id: alidade-20260505-0
file: data/en.wikipedia.org/wiki/Alidade-0.md
category: reference
title: Alidade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alidade
date_saved: 2026-05-05T09:39:56.566183+00:00
instance: kb-cron
parent: alidade-20260505-0
summary:
An alidade () (archaic forms include alhidade, alhidad, alidad) or a turning board is a device that allows one to sight a distant object and use the line of sight to perform a task. This task can be, for example, to triangulate a scale map on site using a plane table drawing of intersecting lines in the direction of the object from two or more points or to measure the angle and horizontal distance to the object from some reference point's polar measurement. Angles measured can be horizontal, vertical or in any chosen plane. The alidade sighting ruler was originally a part of many types of scientific and astronomical instrument. At one time, some alidades, particularly using circular graduations as on astrolabes, were also called diopters. With modern technology, the name is applied to complete instruments such as the 'plane table alidade'. == Origins == The word in Arabic (الحلقة العضدية, al-ḥilqa al-ʿaḍudiyya, lit. 'the ruler'), signifies the same device. In Greek and Latin, it is respectively called δίοπτρα, "dioptra", and linea fiduciae, "fiducial line". The earliest alidades consisted of a bar, rod or similar component with a vane on each end. Each vane (also called a pinnule or pinule)


id: almucantar-20260505-0
file: data/en.wikipedia.org/wiki/Almucantar-0.md
category: reference
title: Almucantar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Almucantar
date_saved: 2026-05-05T09:39:57.899944+00:00
instance: kb-cron
parent: almucantar-20260505-0
summary:
An almucantar (also spelled almucantarat or almacantara) is a circle on the celestial sphere parallel to the horizon. Two stars that lie on the same almucantar have the same altitude. The term was introduced into European astronomy by monastic astronomer Hermann Contractus of Reichenau, Latinized from the Arabic word al-muqanṭarah ("the almucantar, sundial", plural: al-muqanṭarāt), derived from qanṭarah ("arch, bridge") == Almucantar staff == An almucantar staff is an instrument chiefly used to determine the time of sunrise and sunset, in order to find the amplitude and consequently the variations of the compass. Usually made of pear tree or boxwood, with an arch of 15° to 30°, it is an example of a backstaff. The sun casts that shadow of a vane (B in the adjacent image) on a horizon vane (A). The horizon vane has a slit or hole to allow the observer to see the horizon in the distance. The observer aligns the horizon and shadow so they show at the same point on the horizon vane and sets the sighting vane (C) to align his line of sight with the horizon. The altitude of the sun is the angle between the shadow vane and the sighting vane


id: antikythera-mechanism-20260505-0
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-0.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
The Antikythera mechanism ( AN-tik-ih-THEER-ə, US also AN-ty-kih-) is an ancient Greek hand-powered orrery (model of the Solar System). It is the oldest known example of an analogue computer. It could be used to predict astronomical positions and eclipses decades in advance. It could also be used to track the four-year cycle of athletic games similar to an olympiad, the cycle of the ancient Olympic Games. The artefact was among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera in 1901. In 1902, during a visit to the National Archaeological Museum in Athens, it was noticed by Greek politician Spyridon Stais as containing a gear, prompting the first study of the fragment by his cousin, Valerios Stais, the museum director. The device, housed in the remains of a wooden-framed case of (uncertain) overall size 34 cm × 18 cm × 9 cm (13.4 in × 7.1 in × 3.5 in), was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is about 13 cm (5 in) in diameter


id: antikythera-mechanism-20260505-1
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-1.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
=== Origin === The Antikythera mechanism is generally referred to as the first known analogue computer. The quality and complexity of the mechanism's manufacture suggests it must have had undiscovered predecessors during the Hellenistic period. Its construction relied on theories of astronomy and mathematics developed by Greek astronomers during the second century BC, and it is estimated to have been built in the late second century BC or the early first century BC. In 2008, research by the Antikythera Mechanism Research Project suggested the concept for the mechanism may have originated in the colonies of Corinth, since they identified the calendar on the Metonic Spiral as coming from Corinth, or one of its colonies in northwest Greece or Sicily. Syracuse was a colony of Corinth and the home of Archimedes, and the Antikythera Mechanism Research Project argued in 2008 that it might imply a connection with the school of Archimedes. It was demonstrated in 2017 that the calendar on the Metonic Spiral is of the Corinthian type, but cannot be that of Syracuse. Another theory suggests that coins found by Jacques Cousteau at the wreck site in the 1970s date to the time of the device's construction, and posits that


id: antikythera-mechanism-20260505-2
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-2.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
=== Operation === On the front face of the mechanism, there is a fixed ring dial representing the ecliptic, the twelve zodiacal signs marked off with equal 30-degree sectors. This matched with the Babylonian custom of assigning one twelfth of the ecliptic to each zodiac sign equally, even though the constellation boundaries were variable. Outside that dial is another ring which is rotatable, marked off with the months and days of the Sothic Egyptian calendar, twelve months of 30 days plus five intercalary days. The months are marked with the Egyptian names for the months transcribed into the Greek alphabet. The first task is to rotate the Egyptian calendar ring to match the current zodiac points. The Egyptian calendar ignored leap days, so it advanced through a full zodiac sign in about 120 years. The mechanism was operated by turning a small hand crank (now lost) which was linked via a crown gear to the largest gear, the four-spoked gear visible on the front of fragment A, gear b1. This moved the date pointer on the front dial, which would be set to the correct Egyptian calendar day. The year is not selectable, so it is necessary to know the


id: antikythera-mechanism-20260505-3
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-3.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
ΠΑΧΩΝ (Pashons) ΠΑΥΝΙ (Payni) ΕΠΙΦΙ (Epiphi) The other months have been reconstructed; some reconstructions of the mechanism omit the five days of the Egyptian intercalary month. The Zodiac dial contains Greek inscriptions of the members of the zodiac, which is believed to be adapted to the tropical month version rather than the sidereal: ΚΡΙΟΣ (Krios [Ram], Aries) ΤΑΥΡΟΣ (Tauros [Bull], Taurus) ΔΙΔΥΜΟΙ (Didymoi [Twins], Gemini) ΚΑΡΚΙΝΟΣ (Karkinos [Crab], Cancer) ΛΕΩΝ (Leon [Lion], Leo) ΠΑΡΘΕΝΟΣ (Parthenos [Maiden], Virgo) ΧΗΛΑΙ (Chelai [Scorpio's Claw or Zygos], Libra) ΣΚΟΡΠΙΟΣ (Skorpios [Scorpion], Scorpio) ΤΟΞΟΤΗΣ (Toxotes [Archer], Sagittarius) ΑΙΓΟΚΕΡΩΣ (Aigokeros [Goat-horned], Capricorn) ΥΔΡΟΧΟΟΣ (Hydrokhoos [Water carrier], Aquarius) ΙΧΘΥΕΣ (Ichthyes [Fish], Pisces) Also on the zodiac dial are single characters at specific points (see reconstruction at ref). They are keyed to a parapegma, a precursor of the modern day almanac inscribed on the front face above and beneath the dials. They mark the locations of longitudes on the ecliptic for specific stars. The parapegma above the dials reads (square brackets indicate inferred text): The parapegma beneath the dials reads: At least two pointers indicated positions of bodies upon the ecliptic. A lunar pointer indicated the position of the Moon, and a mean Sun pointer was shown, perhaps


id: antikythera-mechanism-20260505-4
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-4.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
The Saros dial is the main lower spiral dial on the rear of the mechanism. The Saros cycle is 18 years and 11+1⁄3 days long (6585.333... days), which is very close to 223 synodic months (6585.3211 days). It is defined as the cycle of repetition of the positions required to cause solar and lunar eclipses, and therefore, it could be used to predict them—not only the month, but the day and time of day. The cycle is approximately 8 hours longer than an integer number of days. Translated into global spin, that means an eclipse occurs not only eight hours later, but one-third of a rotation farther to the west. Glyphs in 51 of the 223 synodic month cells of the dial specify the occurrence of 38 lunar and 27 solar eclipses. Some of the abbreviations in the glyphs read: Σ = ΣΕΛΗΝΗ ("Selene", Moon) Η = ΗΛΙΟΣ ("Helios", Sun) H\M = ΗΜΕΡΑΣ ("Hemeras", of the day) ω\ρ = ωρα ("hora", hour) N\Y = ΝΥΚΤΟΣ ("Nuktos", of the night) The glyphs show whether the designated eclipse is solar or lunar, and give the day of the month and hour. Solar eclipses may not be visible at any given point, and


id: antikythera-mechanism-20260505-5
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-5.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
=== Gearing === The mechanism is remarkable for the level of miniaturisation and the complexity of its parts, which is comparable to that of 14th-century astronomical clocks. It has at least 30 gears, although mechanism expert Michael Wright has suggested the Greeks of this period were capable of implementing a system with many more gears. There is debate as to whether the mechanism had indicators for all five of the planets known to the ancient Greeks. No gearing for such a planetary display survives and all gears are accounted for—with the exception of one 63-toothed gear (r1) otherwise unaccounted for in fragment D. Fragment D is a small quasi-circular constriction that, according to Xenophon Moussas, has a gear inside a somewhat larger hollow gear. The inner gear moves inside the outer gear reproducing an epicyclical motion that, with a pointer, gives the position of planet Jupiter. The inner gear is numbered 45, "ME" in Greek, and the same number is written on two surfaces of this small cylindrical box. The purpose of the front face was to position astronomical bodies with respect to the celestial sphere along the ecliptic, in reference to the observer's position on the Earth. That is


id: antikythera-mechanism-20260505-6
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-6.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
It is very probable there were planetary dials, as the complicated motions and periodicities of all planets are mentioned in the manual of the mechanism. The exact position and mechanisms for the gears of the planets is unknown. There is no coaxial system except for the Moon. Fragment D that is an epicycloidal system, is considered as a planetary gear for Jupiter (Moussas, 2011, 2012, 2014) or a gear for the motion of the Sun (University of Thessaloniki group). The Sun gear is operated from the hand-operated crank (connected to gear a1, driving the large four-spoked mean Sun gear, b1) and in turn drives the rest of the gear sets. The Sun gear is b1/b2 and b2 has 64 teeth. It directly drives the date/mean sun pointer (there may have been a second, "true sun" pointer that displayed the Sun's elliptical anomaly; it is discussed below in the Freeth reconstruction). In this discussion, reference is to modelled rotational period of various pointers and indicators; they all assume the input rotation of the b1 gear of 360 degrees, corresponding with one tropical year, and are computed solely on the basis of the gear ratios of the gears named. The Moon train


id: antikythera-mechanism-20260505-7
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-7.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
=== Proposed gear schemes === Because of the large space between the mean Sun gear and the front of the case and the size of and mechanical features on the mean Sun gear, it is very likely that the mechanism contained further gearing that either has been lost in or subsequent to the shipwreck, or was removed before being loaded onto the ship. This lack of evidence and nature of the front part of the mechanism has led to attempts to emulate what the Ancient Greeks would have done and because of the lack of evidence, many solutions have been put forward over the years. But as progress has been made on analyzing the internal structures and deciphering the inscriptions, earlier models have been ruled out and better models developed. Derek J. de Solla Price built a simple model in the 1970s. In 2002 Michael Wright designed and built the first workable model with the known mechanism and his emulation of a potential planetarium system. He suggested that along with the lunar anomaly, adjustments would have been made for the deeper, more basic solar anomaly (known as the "first anomaly"). He included pointers for this "true sun", Mercury, Venus, Mars,


id: antikythera-mechanism-20260505-8
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-8.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
The system to synthesise the solar anomaly is very similar to that used in Wright's proposal: three gears, one fixed in the centre of the b1 gear and attached to the Sun spindle, the second fixed on one of the spokes (in their proposal the one on the bottom left) acting as an idle gear, and the final positioned next to that one; the final gear is fitted with an offset pin and, over said pin, an arm with a slot that in turn, is attached to the sun spindle, inducing anomaly as the mean Sun wheel turns. The inferior planet mechanism includes the Sun (treated as a planet in this context), Mercury, and Venus. For each of the three systems, there is an epicyclic gear whose axis is mounted on b1, thus the basic frequency is the Earth year (as it is, in truth, for epicyclic motion in the Sun and all the planets—excepting only the Moon). Each meshes with a gear grounded to the mechanism frame. Each has a pin mounted, potentially on an extension of one side of the gear that enlarges the gear, but doesn't interfere with the teeth; in some cases, the needed distance between


id: antikythera-mechanism-20260505-9
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-9.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
In short, the Antikythera Mechanism was a machine designed to predict celestial phenomena according to the sophisticated astronomical theories current in its day, the sole witness to a lost history of brilliant engineering, a conception of pure genius, one of the great wonders of the ancient world—but it didn't really work very well! In addition to theoretical accuracy, there is the issue of mechanical accuracy. Freeth and Jones note that the inevitable "looseness" in the mechanism due to the hand-built gears, with their triangular teeth and the frictions between gears, and in bearing surfaces, probably would have swamped the finer solar and lunar correction mechanisms built into it: Though the engineering was remarkable for its era, recent research indicates that its design conception exceeded the engineering precision of its manufacture by a wide margin—with considerable cumulative inaccuracies in the gear trains, which would have cancelled out many of the subtle anomalies built into its design. While the device may have struggled with inaccuracies, due to the triangular teeth being hand-made, the calculations used and technology implemented to create the elliptical paths of the planets and retrograde motion of the Moon and Mars, by using a clockwork-type gear train with the


id: antikythera-mechanism-20260505-10
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-10.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
Pappus of Alexandria (290 – c. 350 AD) stated that Archimedes had written a now lost manuscript on the construction of these devices titled On Sphere-Making. The surviving texts from ancient times describe many of his creations, some even containing simple drawings. One such device is his odometer, the exact model later used by the Romans to place their mile markers (described by Vitruvius, Heron of Alexandria and in the time of Emperor Commodus). The drawings in the text appeared functional, but attempts to build them as pictured had failed. When the gears pictured, which had square teeth, were replaced with gears of the type in the Antikythera mechanism, which were angled, the device was perfectly functional. If Cicero's account is correct, then this technology existed as early as the third century BC. Archimedes' device is also mentioned by later Roman era writers such as Lactantius (Divinarum Institutionum Libri VII), Claudian (In sphaeram Archimedes), and Proclus (Commentary on the first book of Euclid's Elements of Geometry) in the fourth and fifth centuries. Cicero also said that another such device was built "recently" by his friend Posidonius, "... each one of the revolutions of which brings about the same movement in


id: antikythera-mechanism-20260505-11
file: data/en.wikipedia.org/wiki/Antikythera_mechanism-11.md
category: reference
title: Antikythera mechanism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antikythera_mechanism
date_saved: 2026-05-05T09:39:59.175186+00:00
instance: kb-cron
parent: antikythera-mechanism-20260505-0
summary:
Several exhibitions have been staged worldwide, leading to the main "Antikythera shipwreck" exhibition at the National Archaeological Museum in Athens. As of 2012, the Antikythera mechanism was displayed as part of a temporary exhibition about the Antikythera shipwreck, accompanied by reconstructions made by Ioannis Theofanidis, Derek de Solla Price, Michael Wright, the Thessaloniki University and Dionysios Kriaris. Other reconstructions are on display at the American Computer Museum in Bozeman, Montana, at the Children's Museum of Manhattan in New York, at Astronomisch-Physikalisches Kabinett in Kassel, Germany, at the Archimedes Museum in Olympia, Greece, at the Kotsanas Museum of Ancient Greek Technology in Athens, at the Musée des Arts et Métiers in Paris and at the Western Australian Museum. The National Geographic documentary series Naked Science dedicated an episode to the Antikythera Mechanism entitled "Star Clock BC" that aired on 20 January 2011. A documentary, The World's First Computer, was produced in 2012 by the Antikythera mechanism researcher and film-maker Tony Freeth. In 2012, BBC Four aired The Two-Thousand-Year-Old Computer; it was also aired on 3 April 2013 in the United States on NOVA, the PBS science series, under the name Ancient Computer. It documents the discovery and 2005 investigation of the


id: arcade-20260505-0
file: data/en.wikipedia.org/wiki/ARCADE-0.md
category: reference
title: ARCADE
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ARCADE
date_saved: 2026-05-05T09:40:00.350251+00:00
instance: kb-cron
parent: arcade-20260505-0
summary:
Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a program which utilizes high-altitude balloon instrument package intended to measure the heating of the universe by the first stars and galaxies after the big bang and search for the signal of relic decay or annihilation. In July 2006 a strong residual radio source was found using the radiometer, approximately six times what is predicted by theory. This phenomenon is known as "space roar" and remains an unsolved problem in astrophysics. ARCADE has been funded by the NASA's Science Mission Directorate under the Astronomy and Physics Research and Analysis Suborbital Investigation program. The program is composed of a team led by Alan Kogut of NASA's Goddard Space Flight Center. ARCADE was launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, conducted under the auspices of the Balloon Program Office at Wallops Flight Facility. The balloon flew to an altitude of 120,000 feet (37 km), viewing about 7% of the sky during its observations. The instrument is designed to detect radiation at centimeter wavelengths. The craft contained seven radiometers which were cooled to 2.7 K (−270.45 °C; −454.81 °F) using liquid helium, with the intent to measure temperature differences as


id: archeops-20260505-0
file: data/en.wikipedia.org/wiki/Archeops-0.md
category: reference
title: Archeops
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Archeops
date_saved: 2026-05-05T09:40:01.559118+00:00
instance: kb-cron
parent: archeops-20260505-0
summary:
Archeops was a balloon-borne instrument dedicated to measuring the Cosmic microwave background (CMB) temperature anisotropies. The study of this radiation is essential to obtain precise information on the evolution of the Universe: density, Hubble constant, age of the Universe, etc. To achieve this goal, measurements were done with devices cooled down at 100mK temperature placed at the focus of a warm telescope. To avoid atmospheric disturbance the whole apparatus is placed on a gondola below a helium balloon that reaches 40 km altitude. Archeops has four bands in the millimeter domain (143, 217, 353 and 545 GHz) with a high angular resolution (about 15 arcminutes) in order to constrain small anisotropy scales, as well as a large sky coverage fraction (30%) in order to minimize the intrinsic cosmic variance. == Instrument and flights == The instrument was designed by adapting concepts put forward for the High Frequency Instrument of Planck surveyor (Planck-HFI) and using balloon-borne constraints. Namely, it consists of an open 3He-4He dilution cryostat cooling spiderweb-type bolometers at 100 mK; cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K) and an off-axis Gregorian telescope. The CMB signal is measured by the 143 and 217 GHz


id: argos-optics-system-20260505-0
file: data/en.wikipedia.org/wiki/ARGOS_(optics_system)-0.md
category: reference
title: ARGOS (optics system)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ARGOS_(optics_system)
date_saved: 2026-05-05T09:40:02.754542+00:00
instance: kb-cron
parent: argos-optics-system-20260505-0
summary:
Advanced Rayleigh Guided Ground Layer Adaptive Optics System (ARGOS) is a multi-star adaptive optics system which is built for use with the Large Binocular Telescope (LBT). With ARGOS, both sides of the LBT will be equipped with a multi-laser beacon system and corresponding wavefront sensors. The artificial beacons are created by Rayleigh scattering the Earth's atmosphere using high power pulsed green lasers. The purpose of ARGOS is to generate six artificial laser guides stars to correct the ground layer turbulence above the LBT mirrors. This will decrease the distortions induced by the atmospheric turbulence, and therefore the imaging and spectroscopic capability of LUCIFER, the LBT spectrograph. == References ==


id: armillary-sphere-20260505-0
file: data/en.wikipedia.org/wiki/Armillary_sphere-0.md
category: reference
title: Armillary sphere
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Armillary_sphere
date_saved: 2026-05-05T09:40:04.003517+00:00
instance: kb-cron
parent: armillary-sphere-20260505-0
summary:
An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (on the celestial sphere), consisting of a spherical framework of rings, centered on Earth or the Sun, that represent lines of celestial longitude and latitude and other astronomically important features, such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately, in ancient China possibly as early as the 4th century BC and ancient Greece during the 3rd century BC, with later uses in the Islamic world and Medieval Europe. With the Earth as center, an armillary sphere is known as Ptolemaic. With the Sun as center, it is known as Copernican. The flag of Portugal features an armillary sphere. The armillary sphere is also featured in Portuguese heraldry, associated with the Portuguese discoveries during the Age of Exploration. Manuel I of Portugal, for example, took it as one of his symbols where it appeared on his standard, and on early Chinese export ceramics made for the Portuguese court. In the flag of the Empire of Brazil, the armillary sphere is also


id: armillary-sphere-20260505-1
file: data/en.wikipedia.org/wiki/Armillary_sphere-1.md
category: reference
title: Armillary sphere
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Armillary_sphere
date_saved: 2026-05-05T09:40:04.003517+00:00
instance: kb-cron
parent: armillary-sphere-20260505-0
summary:
The globe assembly is supported on a pedestal N, and may be elevated or depressed upon the joint O, to any number of degrees from 0 to 90 by means of the arc P, which is fixed in the strong brass arm Q. The globe assembly slides in the upright piece R, in which is a screw at r, to fix it at any proper elevation. In the box T are two wheels (as in Dr Long's sphere) and two pinions, whose axes come out at V and U; either of which may be turned by the small winch W. When the winch is put upon the axis V, and turned backward, the terrestrial globe, with its horizon and celestial meridian, keep at rest; and the whole sphere of circles turns round from east, by south, to west, carrying the sun Y, and moon Z, round the same way, and causing them to rise above and set below the horizon. But when the winch is put upon the axis U, and turned forward, the sphere with the sun and moon keep at rest; and the earth, with its horizon and meridian, turn round from horizon to the sun and moon,


id: armillary-sphere-20260505-2
file: data/en.wikipedia.org/wiki/Armillary_sphere-2.md
category: reference
title: Armillary sphere
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Armillary_sphere
date_saved: 2026-05-05T09:40:04.003517+00:00
instance: kb-cron
parent: armillary-sphere-20260505-0
summary:
Throughout Chinese history, astronomers have created celestial globes (Chinese: 渾象; pinyin: húnxiàng) to assist the observation of the stars. The Chinese also used the armillary sphere in aiding calendrical computations and calculations. According to Joseph Needham, the earliest development of the armillary sphere in China goes back to the astronomers Shi Shen and Gan De in the 4th century BC, as they were equipped with a primitive single-ring armillary instrument. This would have allowed them to measure the north polar distance (declination) a measurement that gave the position in a xiu (right ascension). Needham's 4th century BC dating, however, is rejected by British sinologist Christopher Cullen, who traces the beginnings of these devices to the 1st century BC. During the Western Han dynasty (202 BC – 9 AD) additional developments made by the astronomers Luoxia Hong (落下閎), Xiangyu Wangren, and Geng Shouchang (耿壽昌) advanced the use of the armillary in its early stage of evolution. In 52 BC, it was the astronomer Geng Shouchang who introduced the first permanently fixed equatorial ring of the armillary sphere. In the subsequent Eastern Han dynasty (23–220 AD) period, the astronomers Fu An and Jia Kui added the ecliptic ring by 84 AD. With


id: armillary-sphere-20260505-3
file: data/en.wikipedia.org/wiki/Armillary_sphere-3.md
category: reference
title: Armillary sphere
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Armillary_sphere
date_saved: 2026-05-05T09:40:04.003517+00:00
instance: kb-cron
parent: armillary-sphere-20260505-0
summary:
In its simplest form, consisting of a ring fixed in the plane of the equator, the armilla is one of the most ancient of astronomical instruments. Slightly developed, it was crossed by another ring fixed in the plane of the meridian. The first was an equinoctial, the second a solstitial armilla. Shadows were used as indices of the sun's positions, in combinations with angular divisions. When several rings or circles were combined representing the great circles of the heavens, the instrument became an armillary sphere. Armillary spheres were developed by the Hellenistic Greeks and were used as teaching tools already in the 3rd century BC. In larger and more precise forms they were also used as observational instruments. However, the fully developed armillary sphere with nine circles perhaps did not exist until the mid-2nd century AD, during the Roman Empire. Eratosthenes most probably used a solstitial armilla for measuring the obliquity of the ecliptic. Hipparchus probably used an armillary sphere of four rings. The Greco-Roman geographer and astronomer Ptolemy (c. 100 – c. 170 AD) describes his instrument, the astrolabon, in his Almagest. It consisted of at least three rings, with a graduated circle inside of which another could slide,


id: armillary-sphere-20260505-4
file: data/en.wikipedia.org/wiki/Armillary_sphere-4.md
category: reference
title: Armillary sphere
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Armillary_sphere
date_saved: 2026-05-05T09:40:04.003517+00:00
instance: kb-cron
parent: armillary-sphere-20260505-0
summary:
The armillary sphere is commonly used in heraldry and vexillology, being mainly known as a symbol associated with Portugal, the Portuguese Empire and the Portuguese discoveries. In the end of the 15th century, the armillary sphere became the personal heraldic badge of the future King Manuel I of Portugal, when he was still a Prince. The intense use of this badge in documents, monuments, flags and other supports, during the reign of Manuel I, transformed the armillary sphere from a simple personal symbol to a national one that represented the Kingdom of Portugal and in particular its Overseas Empire. As a national symbol, the armillary sphere continued in use after the death of Manuel I. In the 17th century, it became associated with the Portuguese dominion of Brazil. In 1815, when Brazil gained the status of kingdom united with that of Portugal, its coat of arms was formalized as a golden armillary sphere in a blue field. Representing Brazil, the armillary sphere became also present in the arms and the flag of the United Kingdom of Portugal, Brazil and the Algarves. When Brazil became independent as an empire in 1822, the armillary sphere continued to be present in its national


id: astrarium-20260505-0
file: data/en.wikipedia.org/wiki/Astrarium-0.md
category: reference
title: Astrarium
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrarium
date_saved: 2026-05-05T09:40:05.273096+00:00
instance: kb-cron
parent: astrarium-20260505-0
summary:
An astrarium, also called a planetarium, is a medieval astronomical clock made in the 14th century by Italian engineer and astronomer Giovanni Dondi dell'Orologio. The Astrarium was modeled after the Solar System and, in addition to counting time and representing calendar dates and holidays, showed how the planets moved around the celestial sphere in one timepiece. This was its main task, in comparison with the astronomical clock, the main task of which is the actual reading of time. A complex mechanism, it combined the functions of a modern planetarium, clock, and calendar into a singular constructive device. Devices that perform this function were known to have been created prior to the design of Dondi, though relatively little is known about them. It is occasionally erroneously claimed by the details of some sources that the Astrarium was the first mechanical device showing the movements of the planets. == History == === Greek and Roman World === The first astraria were mechanical devices. Archimedes is said to have used a primitive version that could predict the positions of the Sun, the Moon, and the planets. On May 17, 1902, an archaeologist named Valerios Stais discovered that a lump of oxidated material, which


id: astrolabe-20260505-0
file: data/en.wikipedia.org/wiki/Astrolabe-0.md
category: reference
title: Astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrolabe
date_saved: 2026-05-05T09:40:07.689542+00:00
instance: kb-cron
parent: astrolabe-20260505-0
summary:
An astrolabe (Ancient Greek: ἀστρολάβος, romanized: astrolábos, lit. 'star-taker'; Arabic: ٱلأَسْطُرلاب, romanized: al-Asṭurlāb; Persian: ستاره‌یاب, romanized: Setāreyāb) is an astronomical instrument dating to ancient times. It serves as a star chart and physical model of the visible half-dome of the sky. Its various functions also make it an elaborate inclinometer and an analog calculation device capable of working out several kinds of problems in astronomy. In its simplest form it is a metal disc with a pattern of wires, cutouts, and perforations that allows a user to calculate astronomical positions precisely. It is able to measure the altitude above the horizon of a celestial body, day or night; it can be used to identify stars or planets, to determine local latitude given local time (and vice versa), to survey, or to triangulate. It was used in classical antiquity, the Byzantine Empire, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes. The astrolabe, which is a precursor to the sextant, is effective for determining latitude on land or calm seas. Although it is less reliable on the heaving deck of a ship in rough seas, the mariner's astrolabe was developed to solve that


id: astrolabe-20260505-1
file: data/en.wikipedia.org/wiki/Astrolabe-1.md
category: reference
title: Astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrolabe
date_saved: 2026-05-05T09:40:07.689542+00:00
instance: kb-cron
parent: astrolabe-20260505-0
summary:
The spherical astrolabe was a variation of both the astrolabe and the armillary sphere, invented during the Middle Ages by astronomers and inventors in the Islamic world. The earliest description of the spherical astrolabe dates to Al-Nayrizi (fl. 892–902). In the 12th century, Sharaf al-Dīn al-Tūsī invented the linear astrolabe, sometimes called the "staff of al-Tusi", which was "a simple wooden rod with graduated markings, but without sights. It was furnished with a plumb line and a double chord for making angular measurements and bore a perforated pointer". The geared mechanical astrolabe was invented by Abi Bakr of Isfahan in 1235. The first known metal astrolabe in Western Europe is the Destombes astrolabe made from brass in the eleventh century in Portugal. Metal astrolabes avoided the warping that large wooden ones were prone to, allowing the construction of larger and therefore more accurate instruments. Metal astrolabes were heavier than wooden instruments of the same size, making it difficult to use them in navigation. Herman Contractus of Reichenau Abbey, examined the use of the astrolabe in Mensura Astrolai during the 11th century. Peter of Maricourt wrote a treatise on the construction and use of a universal astrolabe in the last half


id: astrolabe-20260505-2
file: data/en.wikipedia.org/wiki/Astrolabe-2.md
category: reference
title: Astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrolabe
date_saved: 2026-05-05T09:40:07.689542+00:00
instance: kb-cron
parent: astrolabe-20260505-0
summary:
Mechanical astronomical clocks were initially influenced by the astrolabe; they could be seen in many ways as clockwork astrolabes designed to produce a continual display of the current position of the sun, stars, and planets. For example, Richard of Wallingford's clock (c. 1330) consisted essentially of a star map rotating behind a fixed rete, similar to that of an astrolabe. Many astronomical clocks use an astrolabe-style display, such as the famous clock at Prague, adopting a stereographic projection (see below) of the ecliptic plane. In recent times, astrolabe watches have become popular. For example, Swiss watchmaker Ludwig Oechslin designed and built an astrolabe wristwatch in conjunction with Ulysse Nardin in 1985. Dutch watchmaker Christaan van der Klauuw also manufactures astrolabe watches today. == Construction == An astrolabe consists of a disk with a wide, raised rim, called the mater (mother), which is deep enough to hold one or more flat plates called tympans, or climates. A tympan is made for a specific latitude and is engraved with a stereographic projection of circles denoting azimuth and altitude and representing the portion of the celestial sphere above the local horizon. The rim of the mater is typically graduated into hours of time,


id: astrolabe-20260505-3
file: data/en.wikipedia.org/wiki/Astrolabe-3.md
category: reference
title: Astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrolabe
date_saved: 2026-05-05T09:40:07.689542+00:00
instance: kb-cron
parent: astrolabe-20260505-0
summary:
The blue sphere represents the celestial sphere. The blue arrow indicates the direction of true north (the North Star). The central blue point represents Earth (the observer's location). The geographic south of the celestial sphere acts as the projection pole. The celestial equatorial plane serves as the projection plane. Three parallel circles represent the projection on the celestial sphere of Earth's main circles of latitude: In orange, the celestial Tropic of Cancer. In purple, the celestial equator. In green, the celestial Tropic of Capricorn. When projecting onto the celestial equatorial plane, three concentric circles correspond to the celestial sphere's three circles of latitude (left side of the image). The largest of these, the projection on the celestial equatorial plane of the celestial Tropic of Capricorn, defines the size of the astrolabe's tympanum. The center of the tympanum (and the center of the three circles) is actually the north-south axis around which Earth rotates, and therefore, the rete of the astrolabe will rotate around this point as the hours of the day pass (due to Earth's rotational motion). The three concentric circles on the tympanum are useful for determining the exact moments of solstices and equinoxes throughout the year: if the


id: astrolabe-20260505-4
file: data/en.wikipedia.org/wiki/Astrolabe-4.md
category: reference
title: Astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astrolabe
date_saved: 2026-05-05T09:40:07.689542+00:00
instance: kb-cron
parent: astrolabe-20260505-0
summary:
== Bibliography == Evans, James (1998), The History and Practice of Ancient Astronomy, Oxford University Press, ISBN 0-19-509539-1 Stöffler, Johannes (2007) [First published 1513], Stoeffler's Elucidatio – The Construction and Use of the Astrolabe [Elucidatio Fabricae Ususque Astrolabii], translated by Gunella, Alessandro; Lamprey, John, John Lamprey, ISBN 978-1-4243-3502-2 King, D. A. (1981), "The Origin of the Astrolabe According to the Medieval Islamic Sources", Journal for the History of Arabic Science, 5: 43–83 King, Henry (1978), Geared to the Stars: the Evolution of Planetariums, Orreries, and Astronomical Clocks, University of Toronto Press, ISBN 978-0-8020-2312-4 Krebs, Robert E.; Krebs, Carolyn A. (2003), Groundbreaking Scientific Experiments, Inventions, and Discoveries of the Ancient World, Greenwood Press, ISBN 978-0-313-31342-4 Laird, Edgar (1997), Carol Poster and Richard Utz (ed.), "Astrolabes and the Construction of Time in the Late Middle Ages", Constructions of Time in the Late Middle Ages, Evanston, Illinois: Northwestern University Press: 51–69 Laird, Edgar; Fischer, Robert, eds. (1995), "Critical edition of Pélerin de Prusse on the Astrolabe (translation of Practique de Astralabe)", Medieval & Renaissance Texts & Studies, Binghamton, New York, ISBN 0-86698-132-2{{citation}}: CS1 maint: work parameter with ISBN (link) Lewis, M. J. T. (2001), Surveying Instruments of Greece and Rome, Cambridge University Press,


id: astronomical-rings-20260505-0
file: data/en.wikipedia.org/wiki/Astronomical_rings-0.md
category: reference
title: Astronomical rings
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_rings
date_saved: 2026-05-05T09:40:08.950204+00:00
instance: kb-cron
parent: astronomical-rings-20260505-0
summary:
Astronomical rings (Latin: annuli astronomici), also known as Gemma's rings, are an early astronomical instrument. The instrument consists of three rings, representing the celestial equator, declination, and the meridian. It can be used as a sun dial to tell time, if the approximate latitude and season is known, or to tell latitude, if the time is known or observed (at solar noon). It may be considered to be a simplified, portable armillary sphere, or a more complex form of astrolabe. == History == Parts of the instrument go back to instruments made and used by ancient Greek astronomers. Gemma Frisius combined several of the instruments into a small, portable, astronomical-ring instrument. He first published the design in 1534, and in Petrus Apianus's Cosmographia in 1539. These ring instruments combined terrestrial and celestial calculations. == Types == === Fixed astronomical rings === Fixed astronomical rings are mounted on a plinth, like armillary spheres, and can be used as sundials. === Traveller's sundial or universal equinoctal ring dial === The dial is suspended from a cord or chain; the suspension point on the vertical meridian ring can be changed to match the local latitude. The time is read off on the equatorial


id: autoguider-20260505-0
file: data/en.wikipedia.org/wiki/Autoguider-0.md
category: reference
title: Autoguider
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Autoguider
date_saved: 2026-05-05T09:40:10.121265+00:00
instance: kb-cron
parent: autoguider-20260505-0
summary:
An autoguider is an automatic electronic guidance tool used in astronomy to keep a telescope pointed precisely at an object being observed. This prevents the object from drifting across the field of view during long-exposures which would create a blurred or elongated image. == Usage == Imaging of dim celestial targets, usually deep sky objects, requires exposure times of many minutes, particularly when narrowband images are being taken. In order for the resulting image to maintain usable clarity and sharpness during these exposures, the target must be held at the same position within the telescope's field of view during the whole exposure; any apparent motion would cause point sources of light (such as stars) to appear as streaks, or the object being photographed to appear blurry. Even computer-tracked mounts and GoTo telescopes do not eliminate the need for tracking adjustments for exposures beyond a few minutes, as astrophotography demands an extremely high level of precision that these devices typically cannot achieve, especially if the mount is not properly polar aligned. To accomplish this automatically an autoguider is usually attached to either a guidescope or finderscope, which is a smaller telescope oriented in the same direction as the main telescope, or


id: backstaff-20260505-0
file: data/en.wikipedia.org/wiki/Backstaff-0.md
category: reference
title: Backstaff
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Backstaff
date_saved: 2026-05-05T09:40:11.293304+00:00
instance: kb-cron
parent: backstaff-20260505-0
summary:
The backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the Sun or Moon. When observing the Sun, users kept the Sun to their back (hence the name) and observed the shadow cast by the upper vane on a horizon vane. It was invented by the English navigator John Davis, who described it in his book Seaman's Secrets in 1594. == Types of backstaffs == Backstaff is the name given to any instrument that measures the altitude of the sun by the projection of a shadow. It appears that the idea for measuring the sun's altitude using back observations originated with Thomas Harriot. Many types of instruments evolved from the cross-staff that can be classified as backstaffs. Only the Davis quadrant remains dominant in the history of navigation instruments. Indeed, the Davis quadrant is essentially synonymous with backstaff. However, Davis was neither the first nor the last to design such an instrument and others are considered here as well. == Davis quadrant == Captain John Davis invented a version of the backstaff in 1594. Davis was a navigator who was quite familiar with the instruments of the day such as the


id: backstaff-20260505-1
file: data/en.wikipedia.org/wiki/Backstaff-1.md
category: reference
title: Backstaff
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Backstaff
date_saved: 2026-05-05T09:40:11.293304+00:00
instance: kb-cron
parent: backstaff-20260505-0
summary:
=== Usage === In order to use the instrument, the navigator would place the shadow vane at a location anticipating the altitude of the sun. Holding the instrument in front of him, with the sun at his back, he holds the instrument so that the shadow cast by the shadow vane falls on the horizon vane at the side of the slit. He then moves the sight vane so that he observes the horizon in a line from the sight vane through the horizon vane's slit while simultaneously maintaining the position of the shadow. This permits him to measure the angle between the horizon and the sun as the sum of the angle read from the two arcs. Since the shadow's edge represents the limb of the sun, he must correct the value for the semidiameter of the sun. === Instruments that derived from the Davis quadrant === The Elton's quadrant derived from the Davis quadrant. It added an index arm with spirit levels to provide an artificial horizon. == Demi-cross == The demi-cross was an instrument that was contemporary with the Davis quadrant. It was popular outside England. The vertical transom was like a half-transom on a cross-staff, hence


id: backstaff-20260505-2
file: data/en.wikipedia.org/wiki/Backstaff-2.md
category: reference
title: Backstaff
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Backstaff
date_saved: 2026-05-05T09:40:11.293304+00:00
instance: kb-cron
parent: backstaff-20260505-0
summary:
== Benjamin Cole quadrant == A late addition to the collection of backstaves in the navigation world, this device was invented by Benjamin Cole in 1748. The instrument consists of a staff with a pivoting quadrant on one end. The quadrant has a shadow vane, which can optionally take a lens like the Davis quadrant's Flamsteed glass, at the upper end of the graduated scale (A in Figure 7). This casts a shadow or projects an image of the sun on the horizon vane (B). The observer views the horizon through a hole in the sight vane (D) and a slit in the horizon vane to ensure the instrument is level. The quadrant component is rotated until the horizon and the sun's image or shadow are aligned. The altitude can then be read from the quadrant's scale. In order to refine the reading, a circular vernier is mounted on the staff (C). The fact that such an instrument was introduced in the middle of the 18th century shows that the quadrant was still a viable instrument even in the presence of the octant. English scientist George Adams created a very similar backstaff at the same time. Adam's version ensured that


id: barcelona-astrolabe-20260505-0
file: data/en.wikipedia.org/wiki/Barcelona_astrolabe-0.md
category: reference
title: Barcelona astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Barcelona_astrolabe
date_saved: 2026-05-05T09:40:12.559441+00:00
instance: kb-cron
parent: barcelona-astrolabe-20260505-0
summary:
The Barcelona astrolabe is the oldest astrolabe with Carolingian characters that has survived in the Christian Occident. The French researcher Marcel Destombes founded the astrolabe, and left it as legacy to the Institute of the Arab World of Paris in 1983. The Academy of Sciences of Barcelona asked the astrolabe in loan to the Musée of l'Institut du Monde Arabe, to make a replica, today this replica is on display at the Academy of Sciences in the Ramblas. == Description == This astrolabe presents some unusual characteristics. All the engraved characters are in Latin, this fact made the scholars think that the instrument was made in Christian Europe. The pointers of his "spider" indicate eighteen stars: ten boreal stars and eight austral stars (that is to say, situated beneath of the equator). Eleven of them correspond to the date of 980 AD. Still like this, the names of the stars are not engraved on the brass. The words ROMA and FRANCIA are engraved in Latin characters in one of the eardrums. These characters are accompanied by the numbers 41-30 (in Arabic figures). The characters are identical to those used at the end of the 10th century in the Catalan Latin


id: bris-sextant-20260505-0
file: data/en.wikipedia.org/wiki/Bris_sextant-0.md
category: reference
title: Bris sextant
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bris_sextant
date_saved: 2026-05-05T09:40:13.805334+00:00
instance: kb-cron
parent: bris-sextant-20260505-0
summary:
The Bris sextant , or Bris Mini-Sextant, is not a sextant proper, but is a small angle-measuring device that can be used for navigation. The Bris is, however, a true reflecting instrument which derives its high accuracy from the same principle of double reflection which is fundamental to the octant, the true sextant, and other reflecting instruments. It differs from other sextants primarily in being a fixed angle sextant, capable of measuring a few specific angles. == History == Sven Yrvind (Lundin) developed his Bris sextant in or before 2007 as part of his quest for low-cost, low-technology equipment for ocean crossings. The Bris is a low-technology, high-precision, fixed-interval instrument. It is made of two narrow, flat pieces of glass (microscope slides) permanently and rigidly mounted in a V-shape to a third flat piece of #12 welding glass to make viewing the sun eye safe. When the sun or moon is viewed through the V, it is split into eight images. The instrument is small and rugged enough that it can be kept in a 35mm film canister (water-tigh, about 3 cm diameter, 4 cm tall) on a lanyard around one's neck. The Bris sextant is calibrated at a known


id: celatone-20260505-0
file: data/en.wikipedia.org/wiki/Celatone-0.md
category: reference
title: Celatone
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Celatone
date_saved: 2026-05-05T09:40:16.196142+00:00
instance: kb-cron
parent: celatone-20260505-0
summary:
The celatone was a device invented by Galileo Galilei to observe Jupiter's moons with the purpose of finding longitude on Earth. It took the form of a piece of headgear with a telescope taking the place of an eyehole. == Modern versions == In 2013, Matthew Dockrey created a replica celatone, using notes from a version created by Samuel Parlour. From April 2014 to January 2015, Dockrey's celatone was on display in the Royal Observatory, Greenwich in east London. == See also == Longitude prize Galilean moons == References == Sobel, Dava (1995). Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. Penguin. ISBN 0-14-025879-5. == External links == Video animation of a Celatone and its use in discovering the longitude for marine navigation Dockrey celatone "Apparatus to render a telescope manageable on shipboard"


id: celestial-sphere-woodrow-wilson-memorial-20260505-0
file: data/en.wikipedia.org/wiki/Celestial_Sphere_Woodrow_Wilson_Memorial-0.md
category: reference
title: Celestial Sphere Woodrow Wilson Memorial
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Celestial_Sphere_Woodrow_Wilson_Memorial
date_saved: 2026-05-05T09:40:17.455936+00:00
instance: kb-cron
parent: celestial-sphere-woodrow-wilson-memorial-20260505-0
summary:
The Celestial Sphere (also known as the Woodrow Wilson Memorial Sphere) is an armillary sphere artpiece situated in the Palais des Nations in Geneva, Switzerland, one of the four headquarters of the United Nations. It was donated in 1939 by the Woodrow Wilson Foundation to what was then the League of Nations building. It is today a symbol of Geneva International and of Geneva as the centre of dialogue and peace. The grounds of the Palais des Nations (seat of the United Nations Office at Geneva) contain many fine objects donated by member states of the United Nations, private sponsors and artists. One of them is the huge—over four-meter-diameter—Celestial Sphere is the chef d'oeuvre of the American sculptor Paul Manship (1885–1966) located in the Ariana Park of the Palais des Nations. == History == Contacted in late 1935 by the Board of the Woodrow Wilson Foundation, Manship was asked to provide an idea for a memorial to President of the United States Woodrow Wilson as the founding father of the League of Nations. At that time the Palais des Nations was still under construction. The first idea for Manship's contribution to the new buildings was to have him design two


id: celestial-sphere-woodrow-wilson-memorial-20260505-1
file: data/en.wikipedia.org/wiki/Celestial_Sphere_Woodrow_Wilson_Memorial-1.md
category: reference
title: Celestial Sphere Woodrow Wilson Memorial
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Celestial_Sphere_Woodrow_Wilson_Memorial
date_saved: 2026-05-05T09:40:17.455936+00:00
instance: kb-cron
parent: celestial-sphere-woodrow-wilson-memorial-20260505-0
summary:
=== Dysfunctional rotation system and illumination === Due to the outbreak of the Second World War the rotation motor of the Celestial Sphere was used for several months only. In the files of the Woodrow Wilson Foundation, the following brief description was found: "A complex silence and solitude reigned; the great ceremony of dedication, with the 30th Assembly in session, had become impossible: only an occasional chance visitor and a few especially interested Americans watched the Italians putting the great sphere, representative of universal comity, into its place of high honour." The rotation motor of the Celestial Sphere was not used during 1940–1945 and ceased to function in the early 1960s. === Deteriorating conditions === The sphere began to have significant problems as early as 1942. The alloy used by the Bearzi Atelier contracted so sharply during the winter that a considerable amount of water could and did enter the hollow constellations. The freezing of that water caused the metal to crack. Already several of the constellations had to be repaired in 1942–43 and at least one cover of a meridian had to be replaced after falling off. "Weep holes" were drilled in all the constellations at that time to


id: center-for-detectors-20260505-0
file: data/en.wikipedia.org/wiki/Center_for_Detectors-0.md
category: reference
title: Center for Detectors
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Center_for_Detectors
date_saved: 2026-05-05T09:40:18.644024+00:00
instance: kb-cron
parent: center-for-detectors-20260505-0
summary:
The Center for Detectors (CfD) is a Rochester Institute of Technology College of Science academic research center. The CfD, established in January 2010 by Dr. Donald Figer, began as an expansion of the Rochester Imaging Detector Laboratory. Its mission is to enable scientific discovery, national security, better living, and commercial innovation through the design and development of advanced photon detectors and associated technology. The CfD designs, develops, and implements new advanced sensor technologies through collaboration with academic researchers, industry engineers, government scientists, and university students. The mission of the CfD is to enable scientific discovery, national security, better living, and commercial innovation through the design and development of advanced photon detectors and associated technology in a broad array of applications (e.g. astrophysics, biomedical imaging, Earth system science, and inter-planetary travel). == Research == The CfD uses a multi-disciplinary approach, spanning the many branches of engineering, imaging science, physics and astronomy. Research pillars of the CfD include, Detectors and Instrumentation, Observational Astrophysics, Wideband Gap Materials, Nanostructures, and Silicon Photonics. === Detectors and Instrumentation === A primary objective of the CfD is the development of advanced detectors and instrumentation for cross-disciplinary applications. Major research projects include the development of detectors that can


id: cherenkov-telescope-array-observatory-20260505-0
file: data/en.wikipedia.org/wiki/Cherenkov_Telescope_Array_Observatory-0.md
category: reference
title: Cherenkov Telescope Array Observatory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cherenkov_Telescope_Array_Observatory
date_saved: 2026-05-05T09:40:19.807251+00:00
instance: kb-cron
parent: cherenkov-telescope-array-observatory-20260505-0
summary:
The Cherenkov Telescope Array Observatory (CTAO) is a multinational project to build a new generation of ground-based gamma-ray instruments in the energy range extending from some tens of GeV to about 300 TeV. It is proposed as an open observatory and will consist of two arrays of imaging atmospheric Cherenkov telescopes, a first array in the Northern Hemisphere, on the Spanish island of La Palma, with emphasis on the study of extragalactic objects at the lowest possible energies, and a second array in the Southern Hemisphere, in the Atacama Desert in Chile, which is to cover the full energy range and concentrate on galactic sources. The physics program of the CTAO goes beyond high-energy astrophysics into cosmology and fundamental physics. Building on the technology of current-generation ground-based gamma-ray detectors (MAGIC, HESS, and VERITAS), the CTAO will be ten times more sensitive and have unprecedented accuracy in its detection of high-energy gamma rays. Current gamma-ray telescope arrays host up to five individual telescopes, but the CTAO is designed to detect gamma rays over a larger area and a wider range of views, with more than 60 telescopes located in the northern and southern hemispheres. In January 2025, the CTAO was established


id: chronocinematograph-20260505-0
file: data/en.wikipedia.org/wiki/Chronocinematograph-0.md
category: reference
title: Chronocinematograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chronocinematograph
date_saved: 2026-05-05T09:40:20.990137+00:00
instance: kb-cron
parent: chronocinematograph-20260505-0
summary:
Chronocinematograph is an astronomical instrument consisting of a film camera, chronometer and chronograph. The device records images using a more precise timetable for observing an eclipse. It was invented in 1927 by a Polish astronomer, mathematician and geodesist Tadeusz Banachiewicz for observing total solar eclipses. During the same year, Banachiewcz used his device for solar observations in Lapland (Sweden), then in the US (1932) and Greece, Japan and Siberia (1936). The invention enhanced the precision for determining the time of an eclipse, due to more precisely timed photos of Baily's beads, and quantifying the duration of totality. This could not have been observed as closely as before due to the brightness of the sun. == References ==


id: astronomical-clock-20260505-0
file: data/en.wikipedia.org/wiki/Astronomical_clock-0.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
An astronomical clock, horologium, or orloj is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the Sun, Moon, zodiacal constellations, and major planets. == Definition == The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes for indicating eclipses), or a rotating star map. The term should not be confused with an astronomical regulator, a high precision but otherwise ordinary pendulum clock used in observatories. Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the Solar System. The Sun is often represented by a golden sphere (as it initially appeared in the Antikythera mechanism, back in the 2nd century BC), shown rotating around the Earth once a day around a 24-hour analog dial. This


id: astronomical-clock-20260505-1
file: data/en.wikipedia.org/wiki/Astronomical_clock-1.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
Most astronomical clocks have a 24-hour analog dial around the outside edge, numbered from I to XII then from I to XII again. The current time is indicated by a golden ball or a picture of the sun at the end of a pointer. Local noon is usually at the top of the dial, and midnight at the bottom. Minute hands are rarely used. The Sun indicator or hand gives an approximate indication of both the Sun's azimuth and altitude. For azimuth (bearing from the north), the top of the dial indicates South, and the two VI points of the dial East and West. For altitude, the top is the zenith and the two VI and VI points define the horizon. (This is for the astronomical clocks designed for use in the northern hemisphere.) This interpretation is most accurate at the equinoxes, of course. If XII is not at the top of the dial, or if the numbers are Arabic rather than Roman, then the time may be shown in Italian hours (also called Bohemian, or Old Czech, hours). In this system, 1 o'clock occurs at sunset, and counting continues through the night and into the next afternoon, reaching 24


id: astronomical-clock-20260505-2
file: data/en.wikipedia.org/wiki/Astronomical_clock-2.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
=== "Dragon" hand: eclipse prediction and lunar nodes === The Moon's orbit is not in the same plane as the Earth's orbit around the Sun but crosses it in two places. The Moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending lunar nodes. Solar and lunar eclipses will occur only when the Moon is positioned near one of these nodes because at other times the Moon is either too high or too low for an eclipse to be seen on the Earth. Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial, with its length extended out to both sides of the dial to pointing at two opposite points on the solar or lunar dial. This so-called "dragon" hand makes one complete rotation around the ecliptic dial every 19 years. It is sometimes decorated with the figure of a serpent or lizard (Greek: drakon) with its snout and tail-tip touching the outer dial, traditionally labelled Latin: "caput draconam" and Latin:


id: astronomical-clock-20260505-3
file: data/en.wikipedia.org/wiki/Astronomical_clock-3.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
=== Watches === More recently, independent clockmaker Christiaan van der Klaauw created a wristwatch astrolabe, the "Astrolabium" in addition to the "Planetarium 2000", the "Eclipse 2001" and the "Real Moon." Ulysse Nardin also sells several astronomical wristwatches, the "Astrolabium," "Planetarium", and the "Tellurium J. Kepler." === Other examples === Two of Holland America's cruise ships, the MS Rotterdam and the MS Amsterdam, both have large astronomical clocks as their main centerpieces inside the ships' atriums. == Examples by country == === Austria === Innsbruck. The astronomical clock in the gable of 17–19 Maria-Theresien-Strasse is a 20th-century copy of the astronomical clock of the Ulm Rathaus in Germany. Peuerbach. The facade of Peuerbach Town Hall features an astrolabe clock, an enlarged copy of Georg von Peuerbach's original astrolabe of 1457. === Belgium === Lier. The Zimmer tower houses an astronomical clock installed by Louis Zimmer in 1930. On twelve dials surrounding a central clockface, it gives indications including the time around the world, the date, the moon phase, and the equation of time, and includes a tide clock. Senzeilles. The Senzeilles astronomical clock was constructed by self-taught Lucien Charloteaux between 1896 and 1912. A domestic clock housed in a wooden case,


id: astronomical-clock-20260505-4
file: data/en.wikipedia.org/wiki/Astronomical_clock-4.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
Auxerre. The 15th-century clock in the Tour de l'Horloge has a 24-hour sun hand and a moon hand which completes a revolution in a lunar day of 24 hours 50 minutes, and shows the lunar phase on a rotating moon ball. Beauvais. The Beauvais astronomical clock in Beauvais Cathedral, constructed 1865–1868 by Auguste-Lucien Vérité, has 52 dials that display the times of sunrise, sunset, moonrise, moonset, the phases of the moon, the solstices, the position of the planets, the current time in 18 cities around the world, and the tidal hours. Its 68 automata enact the Last Judgement on the hour. Besançon. The Besançon astronomical clock in Besançon Cathedral (1860) was also constructed by Auguste-Lucien Vérité. Its 70 dials provide 122 indications. Bourges. The Bourges astronomical clock in Bourges Cathedral was installed in 1424. It shows the zodiac, and the moon phase and age. Chartres. The Chartres astronomical clock in Chartres Cathedral is an astrolabe clock, installed in 1528. It was overhauled, its mechanism replaced by an electric mechanism, in 2009. Haguenau. The facade of the Musée alsacien displays an astronomical clock, a modern copy of the clock of the Ulm Rathaus. Lyon. The Lyon astronomical clock in Lyon Cathedral


id: astronomical-clock-20260505-5
file: data/en.wikipedia.org/wiki/Astronomical_clock-5.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
A group of interior astronomical clocks of the 14th, 15th and 16th centuries in churches of Hanseatic League towns in northern Germany, known as the Hanseatic clocks (the group also includes the clock at Gdańsk, now in Poland). Bad Doberan. At Doberan Minster, an astrolabe clock was installed by Nikolaus Lilienfeld in 1390. Only the dial survives, now positioned above the west door. Lübeck. The astronomical clock of St. Mary's Church, constructed 1561–1566, was destroyed in the bombing of Lübeck in 1942. The present clock is a replacement by Paul Behrens, installed in 1967. Münster. The Münster astronomical clock of 1540 in Münster Cathedral, adorned with hand-painted zodiac symbols, which traces the movement of the planets, plays a glockenspiel tune every noon. Rostock. The Rostock astronomical clock in St. Mary's Church dating from 1472, built by Hans Düringer. Clock with daily time, zodiac, moon phases, and month. With a dedicated electronic database this clock is particularly well documented. Stendal. At St. Mary's Church, an astronomical clock of the 1580s, rebuilt in 1856 (and vandalized by the clockmaker), and restored in 1977. Stralsund. The astronomical clock in St. Nicholas' Church is an astrolabe clock installed by Nikolaus Lilienfeld in 1394. It


id: astronomical-clock-20260505-6
file: data/en.wikipedia.org/wiki/Astronomical_clock-6.md
category: reference
title: Astronomical clock
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Astronomical_clock
date_saved: 2026-05-05T09:40:22.228447+00:00
instance: kb-cron
parent: astronomical-clock-20260505-0
summary:
=== Malta === Valletta. The clock of the Grandmaster's Palace, installed in 1745, shows the hour, date, month, and lunar phase, and has bells struck by four jacquemarts. Malta has several church clocks that show calendar indications on separate dials, including those of St John's Co-Cathedral, Valletta; St Paul's Cathedral, Mdina; the Rotunda of Mosta; and the Church of St Bartholomew, Għargħur. === Netherlands === Arnemuiden. The 16th-century church clock at Arnemuiden indicates the lunar phase and the time of high tide. Franeker. The Eise Eisinga Planetarium, built 1774–1781, is an orrery and astronomical clock which shows the movements of the solar system. === Norway === Oslo. A 20th-century astronomical clock at Oslo City Hall. === Poland === Gdańsk. In St. Mary's Church there is the Gdańsk astronomical clock dating from 1464 to 1470, and built by Hans Düringer of Toruń. It was reconstructed after 1945. Wrocław. A 16th-century clock showing the moon phase at Wrocław Town Hall. === Slovakia === Stará Bystrica: An astronomical clock in the stylized shape of Our Lady of Sorrows was built in the town square in 2009. The astronomical part of the clock consists of an astrolabe displaying the astrological signs, positions of the


id: cosmolabe-20260505-0
file: data/en.wikipedia.org/wiki/Cosmolabe-0.md
category: reference
title: Cosmolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cosmolabe
date_saved: 2026-05-05T09:40:24.500974+00:00
instance: kb-cron
parent: cosmolabe-20260505-0
summary:
The cosmolabe was an ancient astronomical instrument resembling the astrolabe, formerly used for measuring the angles between heavenly bodies. It is also called pantacosm. Jacques Besson also uses this name, or universal instrument, for his invention described in Le cosmolabe (1566), which could be used for astrometry, cartography, navigation, and surveying. The Cosmolabe is a comprehensive and versatile astronomical instrument designed to perform a wide range of observations and calculations. It was created to serve as a universal tool, capable of replacing several different instruments used in astronomy, geometry, and navigation. According to the inventor, the Cosmolabe can perform the functions of the Sphere, various types of Astrolabes (including the Armillary of Ptolemy, the Torquetum, and the Triquetrum), Jacob’s staff, the Geometric Square, the astronomical quadrant, and even celestial and terrestrial globes. The instrument is designed to be leveled precisely with the horizon, and it can be used on any flat plane, regardless of its inclination. With the Cosmolabe, users can easily determine the meridian line, find the vertical and horizontal circles (almucantarats and height circles), and represent all circles of declination on a given horizon. Additionally, the Cosmolabe can be used to mark meridional circles and find the great


id: cranmer-park-20260505-0
file: data/en.wikipedia.org/wiki/Cranmer_Park-0.md
category: reference
title: Cranmer Park
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cranmer_Park
date_saved: 2026-05-05T09:40:25.682353+00:00
instance: kb-cron
parent: cranmer-park-20260505-0
summary:
Cranmer Park is a city park in Denver, United States located in the Hilltop neighborhood off Colorado Boulevard between East 1st and East 3rd Avenue. It is notable for its large sundial. An inscription at the base describes the axis of the gnomon as elevated 39°43' in the direction of polar north. The stone is perpendicular to the gnomon at 50°17', which makes it parallel to the equator. The south side of the stone is similarly marked for wintertime observation. A polar chart at the base of the sundial describes the zodiac and degrees of the sun's position, and how to set a clock based on the gnomon's shadow. For winter viewing, the chart continues on the south side of the stone. == History of the sundial == The current sundial is the second one to exist at this location in the park. The first was donated in 1941 by longtime Manager of Denver Parks George E. Cranmer, for whom the park is named. It was destroyed by vandals who exploded dynamite under it in September 1965. The replacement sundial was installed in March, 1966 after a successful citywide fundraising effort led by the Denver Junior Chamber of Commerce. It


id: dioptra-20260505-0
file: data/en.wikipedia.org/wiki/Dioptra-0.md
category: reference
title: Dioptra
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dioptra
date_saved: 2026-05-05T09:40:31.436883+00:00
instance: kb-cron
parent: dioptra-20260505-0
summary:
A dioptra (sometimes also named dioptre or diopter, from Greek: διόπτρα) is a classical astronomical and surveying instrument, dating from the 3rd century BC. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles. == Use == Greek astronomers used the dioptra to measure the positions of stars; both Euclid and Geminus refer to the dioptra in their astronomical works. It continued in use as an effective surveying tool. Adapted to surveying, the dioptra is similar to the theodolite, or surveyor's transit, which dates to the sixteenth century. It is a more accurate version of the groma. There is some speculation that it may have been used to build the Eupalinian aqueduct. Called "one of the greatest engineering achievements of ancient times," it is a tunnel 1,036 metres (3,399 ft) long, excavated through a mountain on the Greek island of Samos during the reign of Polycrates in the sixth century BC. Scholars disagree, however, whether the dioptra was available that early. An entire book about the construction and surveying usage of the dioptra is credited to Hero of Alexandria


id: stanford-dish-stanford-radio-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Stanford_Dish_(Stanford_Radio_Telescope)-0.md
category: reference
title: Stanford Dish (Stanford Radio Telescope)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Stanford_Dish_(Stanford_Radio_Telescope)
date_saved: 2026-05-05T09:40:32.590061+00:00
instance: kb-cron
parent: stanford-dish-stanford-radio-telescope-20260505-0
summary:
The Stanford Dish, known locally as the Dish, is a steerable radio antenna in the Stanford, California foothills. "The Dish" is also used locally to refer to the surrounding hiking area. The 150-foot-diameter (46 m) Dish was built in 1961 by the Stanford Research Institute (now SRI International). The cost to construct the antenna was $4.5 million, and was funded by the United States Air Force. In the 1960s the Dish was used to provide information on Soviet radar installations by detecting radio signals bounced off the moon. Later on, the Dish was used to communicate with satellites and spacecraft. With its unique bistatic range radio communications, where the transmitter and receiver are separate units, the powerful radar antenna was well-suited for communicating with spacecraft in regions where conventional radio signals may be disrupted. At one point, the Dish transmitted signals to each of the Voyager craft that NASA dispatched into the outer reaches of the Solar System. In 1982 it was used to rescue the amateur radio satellite UoSAT-1. == Later uses == As of 2018, the Dish is still actively used for academic and research purposes. It is owned by the U.S. Government and operated by SRI International.


id: dividing-engine-20260505-0
file: data/en.wikipedia.org/wiki/Dividing_engine-0.md
category: reference
title: Dividing engine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dividing_engine
date_saved: 2026-05-05T09:40:33.856511+00:00
instance: kb-cron
parent: dividing-engine-20260505-0
summary:
A dividing engine is a device employed to mark graduations on measuring instruments. == History == There has always been a need for accurate measuring instruments. Whether it is a linear device such as a ruler or vernier or a circular device such as a protractor, astrolabe, sextant, theodolite, or setting circles for astronomical telescopes, the desire for ever greater precision has always existed. For every improvement in the measuring instruments, such as better alidades or the introduction of telescopic sights, the need for more exact graduations immediately followed. In early instruments, graduations were typically etched or scribed lines in wood, ivory or brass. Instrument makers devised various devices to perform such tasks. Early Islamic instrument makers must have had techniques for the fine division of their instruments, as this accuracy is reflected in the accuracy of the readings they made. This skill and knowledge seems to have been lost, given that small quadrants and astrolabes in the 15th and 16th centuries did not show fine graduations and were relatively roughly made. In the 16th century, European instrument makers were hampered by the materials available. Brass was in hammered sheets with rough surfaces and iron graving tools were poor quality.


id: eidouranion-20260505-0
file: data/en.wikipedia.org/wiki/Eidouranion-0.md
category: reference
title: Eidouranion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Eidouranion
date_saved: 2026-05-05T09:40:35.019531+00:00
instance: kb-cron
parent: eidouranion-20260505-0
summary:
An eidouranion is a kind of orrery that combined mechanical movement with a method of back projection. Its invention is attributed to Adam Walker (1731–1821) who in the 1780s built one measuring 27 ft (8.2 m) in diameter. He used it to accompany his lectures on astronomy. It is an ancestor of planetarium projectors. It is known that Adam Walker held lectures featuring the Eidouranium at the Royal Theatre in London in the 1780s and the London Lyceum. The shows were continued by his eldest son, William Walker (1767-1816), from around 1812. The shows were continued through the 1820s by William’s younger brother Deane Franklin Walker (1778-1865). The word "eidouranion" derives from the Greek compound "eid + ouranos". The combining elements are "eidos", which means "what is seen, shape, form", and "ouranos", which was the name of the god of the heavens. Thus, the combined form means "shaped like the heavens" or "formed like the heavens". == References == == Further reading == King, Henry C, and John R. Millburn. Geared to the Stars: The Evolution of Planetariums, Orreries, and Astronomical Clocks. Toronto: University of Toronto Press, 1978. Print. [esp. Ch. 19: The Eidouranion and Other Large Transparent Orreries] ==


id: elodie-spectrograph-20260505-0
file: data/en.wikipedia.org/wiki/ELODIE_spectrograph-0.md
category: reference
title: ELODIE spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ELODIE_spectrograph
date_saved: 2026-05-05T09:40:36.183915+00:00
instance: kb-cron
parent: elodie-spectrograph-20260505-0
summary:
ELODIE was an echelle spectrograph installed on the 1.93m reflector at the Observatoire de Haute-Provence in south-eastern France. Its optical instrumentation was developed by André Baranne from the Marseille Observatory. The purpose of the instrument was extrasolar planet detection by the radial velocity method. ELODIE's first light was achieved in 1993. The instrument was decommissioned in August 2006 and replaced in September 2006 by SOPHIE, a new instrument of the same type but with improved features. == Characteristics == The instrument could observe the electromagnetic spectrum over a wavelength range of 389.5 nm to 681.5 nm in a single exposure, split into 67 spectral orders. The instrument, which was located in a temperature-controlled room, was fed with optical fibers from the Cassegrain focus. The observatory provided an integrated data reduction pipeline which fully reduced the spectra immediately after acquisition and allowed the user to measure radial velocities to an accuracy as good as ±7 m/s. Over 34,000 spectra were taken with ELODIE, over 20,000 of which are publicly available through a dedicated on-line archive. The instrument was the result of a collaboration between the observatories of Haute-Provence, Geneva and Marseille. A publication describing the instrument appeared in Astronomy & Astrophysics


id: elton-s-quadrant-20260505-0
file: data/en.wikipedia.org/wiki/Elton's_quadrant-0.md
category: reference
title: Elton's quadrant
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Elton's_quadrant
date_saved: 2026-05-05T09:40:37.388651+00:00
instance: kb-cron
parent: elton-s-quadrant-20260505-0
summary:
An Elton's quadrant is a derivative of the Davis quadrant. It adds an index arm and artificial horizon to the instrument, and was invented by English sea captain John Elton, who patented his design in 1728 and published details of the instrument in the Philosophical Transactions of the Royal Society in 1732. == Construction == This instrument clearly reflects the shape and features of the Davis quadrant. The significant differences are the change in the upper arc to a simple triangular frame and the addition of an index arm. The triangular frame at the top spans 60° as did the arc on the backstaff. The main graduated arc subtends 30° as in the backstaff. The 30° arc is graduated in degrees and sixths of a degree, that is, at ten-minute intervals. The sighting vane of the backstaff is replaced with a sight (called an eye vane) mounted on the end of the index arm. The index arm includes a nonius to allow reading the large scale with ten divisions between the graduations on the scale. This provides the navigator with the ability to read the scale to the nearest minute of arc. The index arm has a spirit level to


id: equatorial-ring-20260505-0
file: data/en.wikipedia.org/wiki/Equatorial_ring-0.md
category: reference
title: Equatorial ring
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equatorial_ring
date_saved: 2026-05-05T09:40:38.637038+00:00
instance: kb-cron
parent: equatorial-ring-20260505-0
summary:
An equatorial ring was an astronomical instrument used in the Hellenistic world to determine the exact moment of the spring and autumn equinoxes. Equatorial rings were placed before the temples in Alexandria, in Rhodes, and perhaps in other places, for calendar purposes. The easiest way to understand the use of an equatorial ring is to imagine a ring placed vertically in the east-west plane at the Earth's equator. At the time of the equinoxes, the Sun will rise precisely in the east, move across the zenith, and set precisely in the west. Throughout the day, the bottom half of the ring will be in the shadow cast by the top half of the ring. On other days of the year, the Sun passes to the north or south of the ring, and will illuminate the bottom half. For latitudes away from the equator, the ring merely needs to be placed at the correct angle to the equatorial plane. At the Earth's poles, the ring would be horizontal. The equatorial ring was about one to two cubits (45cm–90cm) in diameter. Because the Sun is not a point source of light, the width of the shadow on the bottom half of the


id: equatorium-20260505-0
file: data/en.wikipedia.org/wiki/Equatorium-0.md
category: reference
title: Equatorium
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equatorium
date_saved: 2026-05-05T09:40:39.861425+00:00
instance: kb-cron
parent: equatorium-20260505-0
summary:
An equatorium (plural, equatoria) is an astronomical calculating instrument. It can be used for finding the positions of the Moon, Sun, and planets without arithmetic operations, using a geometrical model to represent the position of a given celestial body. == History == In his comment on Ptolemy's Handy Tables, 4th century mathematician Theon of Alexandria introduced some diagrams to geometrically compute the position of the planets based on Ptolemy's epicyclical theory. The first description of the construction of a solar equatorium (as opposed to planetary) is contained in Proclus's fifth-century work Hypotyposis, where he gives instructions on how to construct one in wood or bronze. The earliest known descriptions of planetary equatoria are in the Latin translation of an early eleventh century text by Ibn al‐Samḥ and a 1080/1081 treatise by al-Zarqālī, contained in the Libros del saber de astronomia (Books of the knowledge of astronomy), a Castilian compilation of astronomical works collected under the patronage of Alfonso X of Castile in the thirteenth century. The Theorica Planetarum (c. 1261–1264) by Campanus of Novara is the earliest extant description of the construction of an equatorium in Latin Europe. Campanus' instrument resembled an astrolabe, with several interchangeable plates within a mater.


id: espresso-20260505-0
file: data/en.wikipedia.org/wiki/ESPRESSO-0.md
category: reference
title: ESPRESSO
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ESPRESSO
date_saved: 2026-05-05T09:40:41.044146+00:00
instance: kb-cron
parent: espresso-20260505-0
summary:
ESPRESSO (Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations) is a third-generation, fiber-fed, cross-dispersed, echelle spectrograph mounted on the European Southern Observatory's Very Large Telescope (VLT). The unit saw its first light with one VLT in December 2017 and first light with all four VLT units in February 2018. ESPRESSO is the successor of a line of echelle spectrometers that include CORAVEL, Elodie, Coralie, and HARPS. It measures changes in the light spectrum with great sensitivity, and is being used to search for Earth-size rocky exoplanets via the radial velocity method. For example, Earth induces a radial-velocity variation of 9 cm/s on the Sun; this gravitational "wobble" causes minute variations in the color of sunlight, invisible to the human eye but detectable by the instrument. The telescope light is fed to the instrument, located in the VLT Combined-Coude Laboratory 70 meters away from the telescope, where the light from up to four unit telescopes of the VLT can be combined. == Sensitivity == ESPRESSO builds on the foundations laid by the High Accuracy Radial Velocity Planet Searcher (HARPS) instrument at the 3.6-metre telescope at ESO's La Silla Observatory. ESPRESSO benefits not only from the much larger combined light-collecting capacity


id: espresso-20260505-1
file: data/en.wikipedia.org/wiki/ESPRESSO-1.md
category: reference
title: ESPRESSO
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/ESPRESSO
date_saved: 2026-05-05T09:40:41.044146+00:00
instance: kb-cron
parent: espresso-20260505-0
summary:
== Status == All design work was completed and finalised by April 2013, with the manufacturing phase of the project commencing thereafter. ESPRESSO was tested on June 3, 2016. ESPRESSO first light occurred on September 25, 2016, during which they spotted various objects, among them the star 60 Sgr A. After being shipped to Chile, installed at the VLT, ESPRESSO saw its first light there on 27 November 2017, in 1-UT mode, observing the star Tau Ceti; the first star observed in the 4-UT mode was on February 3, 2018. A problem was discovered in the ESPRESSO charge-coupled device controllers, digital imaging hardware, where a differential nonlinearity issue has reduced the resolution obtainable more severely than was previously feared. The ESO detector team that determined the source of the problem is currently, as of June 2019, working on a new version of the associated hardware in order to remedy this hopefully temporary setback. On August 29, 2019, the ESPRESSO ETC was updated to reflect the gain in transmission after the technical mission of July. This gain influx was, on average, ≈50% in the UHR and HR modes and ≈40% in the MR. As of April 6, 2020, the red radial


id: european-pulsar-timing-array-20260505-0
file: data/en.wikipedia.org/wiki/European_Pulsar_Timing_Array-0.md
category: reference
title: European Pulsar Timing Array
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/European_Pulsar_Timing_Array
date_saved: 2026-05-05T09:40:42.221887+00:00
instance: kb-cron
parent: european-pulsar-timing-array-20260505-0
summary:
The European Pulsar Timing Array (EPTA) is a European collaboration to combine five 100-m class radio-telescopes to observe an array of pulsars with the specific goal of detecting gravitational waves. It is one of several pulsar timing array projects in operation, and one of the four projects comprising the International Pulsar Timing Array, the others being the Parkes Pulsar Timing Array, the North American Nanohertz Observatory for Gravitational Waves, and the Indian Pulsar Timing Array. == Pulsars and high-precision timing == Pulsars are rapidly rotating, highly magnetised neutron stars that emit radio waves from their magnetic poles that are, due to the star's rotation, observed on Earth as a string of pulses. Due to the extremely high density of neutron stars, their rotation periods are very stable, hence the observed arrival time of the pulses are highly regular. These arrival times are called TOAs (time of arrival) and can be used to perform high-precision timing experiments. The stability of the TOAs from most pulsars is limited due to the presence of red noise, also called "timing noise". However, there is a special class of pulsars, called millisecond pulsars (MSP), that are shown to suffer from little or no timing noise.


id: expres-20260505-0
file: data/en.wikipedia.org/wiki/EXPRES-0.md
category: reference
title: EXPRES
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/EXPRES
date_saved: 2026-05-05T09:40:44.606027+00:00
instance: kb-cron
parent: expres-20260505-0
summary:
The EXtreme PREcision Spectrograph (EXPRES) is an optical fiber fed echelle instrument designed and built at the Yale Exoplanet Laboratory to be installed on the 4.3-meter Lowell Discovery Telescope operated by Lowell Observatory. It has a goal to achieve 10 cm/s radial velocity precision. It uses a laser frequency comb to calibrate the primary wavelength for EXPRES. == See also == ESPRESSO spectrograph HARPS3 == References ==


id: fiber-optic-improved-next-generation-doppler-search-for-exo-earths-20260505-0
file: data/en.wikipedia.org/wiki/Fiber-optic_Improved_Next-generation_Doppler_Search_for_Exo-Earths-0.md
category: reference
title: Fiber-optic Improved Next-generation Doppler Search for Exo-Earths
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fiber-optic_Improved_Next-generation_Doppler_Search_for_Exo-Earths
date_saved: 2026-05-05T09:40:45.746135+00:00
instance: kb-cron
parent: fiber-optic-improved-next-generation-doppler-search-for-exo-earths-20260505-0
summary:
The Fiber-Optic Improved Next-Generation Doppler Search for Exo-Earths (FINDS Exo-Earths) is a radial-velocity spectrograph developed by Debra Fischer. It is installed on the 3 meter telescope in Lick Observatory in Mount Hamilton. It has been in operation since 2009 and is being used to verify exoplanet candidates found by the Kepler space telescope. At Yale University, Debra Fischer and Julien Spronck, along with Geoff Marcy of the University of California, Berkeley, set out to improve existing spectrograph technologies. Spurred by a $45,000 grant from The Planetary Society, the team built FINDS, a spectrograph add-on device. == See also == List of potentially habitable exoplanets Similar instruments CORALIE spectrograph ELODIE spectrograph, the precursor instrument ESPRESSO, a new-generation spectrograph for ESO's VLT HARPS SOPHIE échelle spectrograph == References ==


id: filar-micrometer-20260505-0
file: data/en.wikipedia.org/wiki/Filar_micrometer-0.md
category: reference
title: Filar micrometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Filar_micrometer
date_saved: 2026-05-05T09:40:46.991471+00:00
instance: kb-cron
parent: filar-micrometer-20260505-0
summary:
A filar micrometer is a specialized eyepiece used in astronomical telescopes for astrometry measurements, in microscopes for specimen measurements, and in alignment and surveying telescopes for measuring angles and distances on nearby objects. "Filar" derives from the Latin filum ("thread"). It refers to the fine threads or wires used in the device. == Construction and use == A typical filar micrometer consists of a reticle that has two fine parallel wires or threads that can be moved by the observer using a micrometer screw mechanism. The wires are placed in the focal image plane of the eyepiece so they remain sharply superimposed over the object under observation, while the micrometer motion moves the wires across the focal plane. Other designs employ a fixed reticle, against which one wire or a second reticle moves. By rotating the eyepiece assembly in the eyetube, the measurement axis can be aligned to match the orientation of the two points of observation. At one time, it was common to use spider silk as a thread. By placing one wire over one point of interest and moving the other to a second point, the distance between the two wires can be measured with the micrometer portion


id: giant-radio-array-for-neutrino-detection-20260505-0
file: data/en.wikipedia.org/wiki/Giant_Radio_Array_for_Neutrino_Detection-0.md
category: reference
title: Giant Radio Array for Neutrino Detection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Giant_Radio_Array_for_Neutrino_Detection
date_saved: 2026-05-05T09:40:48.179050+00:00
instance: kb-cron
parent: giant-radio-array-for-neutrino-detection-20260505-0
summary:
The Giant Radio Array for Neutrino Detection (GRAND) is a proposed large-scale detector designed to collect ultra-high energy cosmic particles as cosmic rays, neutrinos and photons with energies exceeding 1017 eV. This project aims at solving the mystery of their origin and the early stages of the universe itself. The proposal, formulated by an international group of researchers, calls for an array of 200,000 receivers to be placed on mountain ranges around the world. == Overview == The GRAND detector would search for neutrinos, exotic particles emitted by some and the black holes in the center of galaxies. These neutrinos could help astronomers find the source of other energetic particles called ultra-high-energy cosmic rays. When neutrinos reach Earth, they often collide with particles either in the air or on the ground, creating showers of secondary particles. These secondary particles can be picked up by the radio antennas, which lets researchers calculate the trajectory of the initial neutrinos and trace them back to their source. The concept was first published in 2017. The giant radio detector array would comprise 200,000 low-cost antennas in groups of 10,000 spread out over nearly 200,000 square kilometres (77,000 sq mi) at different locations around the


id: globe-of-matelica-20260505-0
file: data/en.wikipedia.org/wiki/Globe_of_Matelica-0.md
category: reference
title: Globe of Matelica
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Globe_of_Matelica
date_saved: 2026-05-05T09:40:49.395028+00:00
instance: kb-cron
parent: globe-of-matelica-20260505-0
summary:
The Globe of Matelica (Globo of Matelica) is an Ancient Greek sundial sculpted on a marble ball. The artifact was found during the 1985 reconstruction of the medieval Palazzo Pretorio, presently Museo Civico Archeologico, of Matelica in the Marches, region of Italy. == Description == The globe measures nearly 29 cm in diameter and appears to be sculpted from a crystalline marble originating near Ephesus in present-day Turkey. It is thought to date from the first two centuries CE. There is one similar item, identified in 1939 by Carl William Blegen in a Museum in Nafplio, Greece. All that remains is the stone component, which is engraved with a variety of inscribed lines and letters. The sphere is bisected by a center line, while on its top are three concentric circles of various diameters, intersected by an arc of a circle and on which words in ancient Greek alphabet are still visible. Additionally it features 13 holes, each marked by a Greek letter. In these holes there were - probably - metallic insertions that delineated the hour. In the lower part there is a large conical depression which ends with a big rectangular hole, likely made to secure the base.


id: gnomon-20260505-0
file: data/en.wikipedia.org/wiki/Gnomon-0.md
category: reference
title: Gnomon
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gnomon
date_saved: 2026-05-05T09:40:50.565275+00:00
instance: kb-cron
parent: gnomon-20260505-0
summary:
A gnomon (; from Ancient Greek γνώμων (gnṓmōn) 'one that knows or examines') is the part of a sundial that casts a shadow. The term is used for a variety of purposes in mathematics and other fields, typically to measure directions, position, or time. == History == A painted stick dating from 2300 BC that was excavated at the archeological site of Taosi is the oldest gnomon known in China. The gnomon was widely used in ancient China from the second millennium BC onward in order to determine the changes in seasons, orientation, and geographical latitude. The ancient Chinese used shadow measurements for creating calendars that are mentioned in several ancient texts. According to the collection of Zhou Chinese poetic anthologies Classic of Poetry, one of the distant ancestors of King Wen of the Zhou dynasty used to measure gnomon shadow lengths to determine the orientation around the 14th century BC. The ancient Greek philosopher Anaximander (610–546 BC) is credited with introducing this Babylonian instrument to the Ancient Greeks. The ancient Greek mathematician and astronomer Oenopides used the phrase drawn gnomon-wise to describe a line drawn perpendicular to another. Later, the term was used for an L-shaped instrument like a


id: gnomon-of-saint-sulpice-20260505-0
file: data/en.wikipedia.org/wiki/Gnomon_of_Saint-Sulpice-0.md
category: reference
title: Gnomon of Saint-Sulpice
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gnomon_of_Saint-Sulpice
date_saved: 2026-05-05T09:40:51.817571+00:00
instance: kb-cron
parent: gnomon-of-saint-sulpice-20260505-0
summary:
The Gnomon of Saint-Sulpice is an astronomical measurement device located in the Church of Saint-Sulpice (Église Saint-Sulpice) in Paris, France. It is a gnomon, a device designed to cast a shadow on the ground in order to determine the position of the sun in the sky. In early modern times, other gnomons were also built in several Italian and French churches in order to better calculate astronomical events. Those churches are Santa Maria del Fiore in Florence, San Petronio in Bologna, and the Church of the Certosa in Rome. These gnomons ultimately fell into disuse with the advent of powerful telescopes. == Structure == The gnomon of Saint-Sulpice is composed of different parts that span the breadth of the transept of the church. The church itself is a huge building, the largest church in Paris. The system is first built around a meridian, a line which is strictly oriented along the north-south axis, represented by a brass line set in a strip of white marble on the floor of the church. This is not the Paris Meridian, established by Louis XIV in 1667, which is located a few hundred metres to the east and goes through the Paris Observatory. The


id: gnomon-of-saint-sulpice-20260505-1
file: data/en.wikipedia.org/wiki/Gnomon_of_Saint-Sulpice-1.md
category: reference
title: Gnomon of Saint-Sulpice
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gnomon_of_Saint-Sulpice
date_saved: 2026-05-05T09:40:51.817571+00:00
instance: kb-cron
parent: gnomon-of-saint-sulpice-20260505-0
summary:
Le Monnier further used the gnomon from 1744 to establish the variations of the ecliptic, or the variations in the obliquity of the Earth's axis. The endeavour is recorded on the plaque at the southern end of the meridian, in the South transept: "Pro nutatione axios terren. obliquitate eclipticae" ("for the nutation of the earth's axis and the obliquity of the ecliptic"). As mentioned on a brass plaque that covered the stone plaque, the obliquity of the ecliptic was 23°28'40".69 in 1744. From 1745 to 1791, Le Monnier visited Saint-Sulpice at each summer solstice and, focusing the light with a lens fixed to the opening in the stained-glass window so as to produce a sharp image of the sun on the floor, noted the exact position of the image at noon. From these observations, he calculated a variation of the obliquity of 45" per century (the exact figure is 46".85 per century). === Perihelion === The gnomon also permitted the determination of the date of the earth's perihelion (the moment the earth is closest to the sun in its elliptical trajectory around the sun), by measuring the size of the image of the sun cast on the obelisk and finding


id: gravity-very-large-telescope-20260505-0
file: data/en.wikipedia.org/wiki/GRAVITY_(Very_Large_Telescope)-0.md
category: reference
title: GRAVITY (Very Large Telescope)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/GRAVITY_(Very_Large_Telescope)
date_saved: 2026-05-05T09:40:53.008414+00:00
instance: kb-cron
parent: gravity-very-large-telescope-20260505-0
summary:
GRAVITY is an instrument on the interferometer of the Very Large Telescope (VLTI). It either combines the light of the four Unit Telescopes (UT) or the smaller four Auxiliary Telescopes. The instrument works with adaptive optics and provides a resolution of 4 milliarcseconds (mas) and can measure the position of astronomical objects down to a few 10 microarcseconds (μas). VLTI GRAVITY has a collecting area of 200 m2 and the angular resolution of a 130 m telescope. == Instrument details == GRAVITY was built by a consortium led by the Max Planck Institute for Extraterrestrial Physics. Other partner institutes are from France, Germany, Portugal and the European Southern Observatory. The first light images included the discovery that Theta1 Orionis F in the Trapezium Cluster is a binary. GRAVITY can operate in single-field mode or in dual-field mode. In the dual-field mode it can interfere two astronomical objects at the same time and acquire this way very accurate astrometry. The instrument data can also be used for K-band spectroscopy with three spectral resolutions. GRAVITY has the following sub-components: IR wavefront sensing system CIAO (located at the Unit Telescopes) that will work with the MACAO deformable mirror A polarisation control system to


id: groombridge-transit-circle-20260505-0
file: data/en.wikipedia.org/wiki/Groombridge_Transit_Circle-0.md
category: reference
title: Groombridge Transit Circle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Groombridge_Transit_Circle
date_saved: 2026-05-05T09:40:55.336144+00:00
instance: kb-cron
parent: groombridge-transit-circle-20260505-0
summary:
Groombridge Transit Circle was a meridian transit circle made by Edward Troughton for the English astronomer Stephen Groombridge in 1806, which Groombridge used to compile data for the star catalogue, Catalogue of Circumpolar Stars. The advantage of a transit circle over a mural circle (which can measure polar distances) is that it allows measuring right ascension and declination at the same time. It had an aperture of 3.5 inches and a 5-foot focal length, mounted inside two 4 foot circles on stone piers. Groombridge used the instrument to determine the positions of over 4000 circumpolar stars. It was eventually bought by James South, and it remained at his observatory at Kensington until 1870. == See also == Groombridge 1830 == References == == Further reading == Royal Institution of Great Britain (1823). The Quarterly Journal. Vol. 16. John Murray. p. 189.


id: harps-n-20260505-0
file: data/en.wikipedia.org/wiki/HARPS-N-0.md
category: reference
title: HARPS-N
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/HARPS-N
date_saved: 2026-05-05T09:40:56.481872+00:00
instance: kb-cron
parent: harps-n-20260505-0
summary:
HARPS-N, the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere is a high-precision radial-velocity spectrograph, installed at the Italian Telescopio Nazionale Galileo, a 3.58-metre telescope located at the Roque de los Muchachos Observatory on the island of La Palma, Canary Islands, Spain. HARPS-N is the counterpart for the Northern Hemisphere of the similar HARPS instrument installed on the ESO 3.6 m Telescope at La Silla Observatory in Chile. It allows for planetary research in the northern sky which hosts the Cygnus and Lyra constellations. In particular it allows for detailed follow up research to Kepler mission planet candidates, which are located in the Cygnus constellation region. The instrument's main scientific goals are the discovery and characterization of terrestrial super-Earths by combining the measurements using transit photometry and doppler spectroscopy which provide both, the size and mass of the exoplanet. Based on the resulting density, rocky (terrestrial) Super-Earths can be distinguished from gaseous exoplanets. The HARPS-N Project is a collaboration between the Geneva Observatory (lead), the Center for Astrophysics in Cambridge (Massachusetts), the Universities of St. Andrews and Edinburgh, the Queen's University Belfast, the UK Astronomy Technology Centre and the Italian Istituto Nazionale di Astrofisica. == First light on


id: helioscope-20260505-0
file: data/en.wikipedia.org/wiki/Helioscope-0.md
category: reference
title: Helioscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Helioscope
date_saved: 2026-05-05T09:40:57.686550+00:00
instance: kb-cron
parent: helioscope-20260505-0
summary:
A helioscope is an instrument used in observing the Sun and sunspots. The helioscope was first used by Benedetto Castelli (1578–1643) and refined by Galileo Galilei (1564–1642). The method involves projecting an image of the sun onto a white sheet of paper suspended in a darkened room with the use of a telescope. The first machina helioscopica or helioscope was designed by Christoph Scheiner (1575 –1650) to assist his sunspot observations. In the context of modern astroparticle physics, the term helioscope can also refer to an experiment that seeks to observe hypothetical particles (such as the axion) produced inside the sun. Examples of such helioscope experiments searching for axions include the CERN Axion Solar Telescope and International Axion Observatory. == See also == Solar telescope Heliometer Spectroheliograph Spectrohelioscope == References ==


id: herschel-wedge-20260505-0
file: data/en.wikipedia.org/wiki/Herschel_wedge-0.md
category: reference
title: Herschel wedge
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Herschel_wedge
date_saved: 2026-05-05T09:40:58.849028+00:00
instance: kb-cron
parent: herschel-wedge-20260505-0
summary:
A Herschel wedge or Herschel prism is an optical prism used in solar observation to refract most of the light out of the optical path, allowing safe visual observation. It was first proposed and used by astronomer John Herschel in the 1830s. == Overview == The prism in a Herschel wedge has a trapezoidal cross section. The surface of the prism facing the light acts as a standard diagonal mirror, reflecting a small portion of the incoming light at 90 degrees into the eyepiece. The trapezoidal prism shape refracts the remainder of the light gathered by the telescope's objective away at an angle. The Herschel wedge reflects about 4.6% of the light that passes through one of the prism faces that is flat to 1/10 of the wavelength of the light. The remaining ~95.4% of the light and heat goes into the prism and exits through the other face and out the back door of the housing; thus, the excess light and heat is disposed of and not used for observing. While they decrease the intensity of the light, they do not affect the visible spectra, resulting in a more accurate spectral profile, which can be filtered to bring out


id: high-accuracy-radial-velocity-planet-searcher-20260505-0
file: data/en.wikipedia.org/wiki/High_Accuracy_Radial_Velocity_Planet_Searcher-0.md
category: reference
title: High Accuracy Radial Velocity Planet Searcher
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/High_Accuracy_Radial_Velocity_Planet_Searcher
date_saved: 2026-05-05T09:41:00.058373+00:00
instance: kb-cron
parent: high-accuracy-radial-velocity-planet-searcher-20260505-0
summary:
The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. HARPS has discovered over 130 exoplanets to date, with the first one in 2004, making it the most successful planet finder behind the Kepler space telescope. It is a second-generation radial-velocity spectrograph, based on experience with the ELODIE and CORALIE instruments. == Characteristics == The HARPS can attain a precision of 0.97 m/s (3.5 km/h), making it one of only two instruments worldwide with such accuracy. This is due to a design in which the target star and a reference spectrum from a thorium lamp are observed simultaneously using two identical optic fibre feeds, and to careful attention to mechanical stability: the instrument sits in a vacuum vessel which is temperature-controlled to within 0.01 kelvins. The precision and sensitivity of the instrument is such that it incidentally produced the best available measurement of the thorium spectrum. Planet-detection is in some cases limited by the seismic pulsations of the star observed rather than by limitations of the instrument. The principal investigator on the HARPS is


id: instrument-of-the-primum-mobile-20260505-0
file: data/en.wikipedia.org/wiki/Instrument_of_the_Primum_Mobile-0.md
category: reference
title: Instrument of the Primum Mobile
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Instrument_of_the_Primum_Mobile
date_saved: 2026-05-05T09:41:02.264020+00:00
instance: kb-cron
parent: instrument-of-the-primum-mobile-20260505-0
summary:
The Instrument of the Primum Mobile is also called the quadrant of Petrus Apianus, because he invented it and described it in the treatise Instrumentum primi mobilis (Nuremberg, 1524). The instrument is used to find sines and cosines. It bears the initials "F.E.D.P.F." [Frater Egnatius Dantis Predicatorum Fecit]. Ignazio Danti dedicated it to Cosimo I de' Medici, as attested by the Medici coat of arms engraved on the front. The instrument was depicted on the ceiling of the Stanzino delle Matematiche in the Uffizi Gallery. == Bibliography == Mara Miniati, ed. (1991). Museo di storia della scienza: catalogo. Firenze: Giunti. p. 44, board n. 28. ISBN 88-09-20036-5. == References == == External links == "Museo Galileo - object description".


id: international-coronelli-society-for-the-study-of-globes-20260505-0
file: data/en.wikipedia.org/wiki/International_Coronelli_Society_for_the_Study_of_Globes-0.md
category: reference
title: International Coronelli Society for the Study of Globes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/International_Coronelli_Society_for_the_Study_of_Globes
date_saved: 2026-05-05T09:41:05.273040+00:00
instance: kb-cron
parent: international-coronelli-society-for-the-study-of-globes-20260505-0
summary:
The International Coronelli Society for the Study of Globes (German: Internationale Coronelli-Gesellschaft für Globenkunde) is a non-profit academic organization devoted to the analysis, restoration and comprehensive study of terrestrial and celestial globes and other cosmographical instruments, such as armillary spheres and planetaria, mainly made before 1850. == History == Founded in Vienna in 1952 by the Austrian engineer and private scholar Robert Haardt (1884–1962), the Society's name is an hommage to Franciscan friar, cosmographer, cartographer, and publisher Vincenzo Coronelli (1650–1718). As of 2023, the Society counts around 300 members from academic institutions around the world. The eponymous Coronelli was not only a renowned producer of large-scale globe pairs, but also the founder of the first geographical society in the world, the Venetian Accademia Cosmografica degli Argonauti. == Activities == Since 1963, it has furthered the study of globe-related topics, including inventorying, restoration and conservation, which have been discussed in dedicated international symposia. The Society awards two international prizes, The International Coronelli-Society Award for Encouragement of Globestudies, and the Fiorini-Haardt Prize for research into pre-1945 globes and their makers. == Publications == Since its foundation in 1952, the society publishes a journal, Der Globusfreund: Wissenschaftliche Zeitschrift für Globenkunde. Since 2002 there


id: international-pulsar-timing-array-20260505-0
file: data/en.wikipedia.org/wiki/International_Pulsar_Timing_Array-0.md
category: reference
title: International Pulsar Timing Array
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/International_Pulsar_Timing_Array
date_saved: 2026-05-05T09:41:06.414535+00:00
instance: kb-cron
parent: international-pulsar-timing-array-20260505-0
summary:
The International Pulsar Timing Array (IPTA) is a multi-institutional, multi-telescope collaboration of pulsar timing arrays (PTAs). It comprises the European Pulsar Timing Array (EPTA), the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), the Parkes Pulsar Timing Array (PPTA) in Australia, the Indian Pulsar Timing Array Project (InPTA), the Chinese Pulsar Timing Array (CPTA), the Meerkat Pulsar Timing Array (MPTA), and African Pulsar Timing (APT). The goal of the IPTA is to detect ultra-low-frequency gravitational waves, such as from mergers of supermassive black holes, using an array of over 100 pulsars. == Overview == The experiment exploits the predictability of the times of arrival (TOAs) of pulses from millisecond pulsars (MSPs) and uses them as a system of galactic clocks. Disturbances in the clocks will be measurable at the Earth. A disturbance from a gravitational wave background will have a particular signature across the ensemble of pulsars called the Hellings & Downs correlation for which multiple PTAs have strong evidence. The experiment is analogous to ground-based interferometric detectors such as LIGO and VIRGO, where the time of flight of a laser beam is measured along a particular path and compared to the time of flight along an orthogonally oriented path.


id: jovilabe-20260505-0
file: data/en.wikipedia.org/wiki/Jovilabe-0.md
category: reference
title: Jovilabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Jovilabe
date_saved: 2026-05-05T09:41:07.586339+00:00
instance: kb-cron
parent: jovilabe-20260505-0
summary:
The jovilabe is a brass scientific instrument, undated and of unknown maker, currently in the collection of the Museo Galileo in Florence, Italy. The jovilabe was used by Galileo Galilei to determine the orbital periods of Jupiter's moons and to compute the times of their eclipses. The instrument is engraved with tables showing the mean motions of each of the four moons. Two connected disks of different diameters are rotated by means of a movable rod. They are used to create a "view from the Sun" of the movements of Jupiter's moons observed from the Earth (movements that seem irregular because of the heliocentric motions of the Earth and Jupiter). After announcing the discovery of Jupiter's moons in his 1610 treatise Sidereus Nuncius, Galileo began the systematic study of their periods in 1611, developing a micrometer for the purpose. Galileo immediately realized that eclipses of the moons could provide a precise method to determine longitude. Galileo compiled tables of the periods that he offered, with his telescopes, first to the King of Spain (1611, 1612, 1616, and 1627-1628), then to the States General of Holland (1637-1641). To convince his Spanish interlocutors that Jupiter and its moons could be observed on


id: large-latin-american-millimeter-array-20260505-0
file: data/en.wikipedia.org/wiki/Large_Latin_American_Millimeter_Array-0.md
category: reference
title: Large Latin American Millimeter Array
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Large_Latin_American_Millimeter_Array
date_saved: 2026-05-05T09:41:08.739089+00:00
instance: kb-cron
parent: large-latin-american-millimeter-array-20260505-0
summary:
The Large Latin American Millimeter Array (LLAMA) is a single-dish 12 m Nasmyth optics antenna which is under construction in the Puna de Atacama desert in the Province of Salta, Argentina, next to the Qubic experiment. The primary mirror accuracy will allow observation from 40 GHz up to 900 GHz. After installation it will be able to join other similar instruments to perform Very Large Base Line Interferometry or to work in standalone mode. Financial support is provided by the Argentinian and Brazilian governments. The total cost of construction, around US$20 million, and operation as well as the telescope time use will be shared equally by the two countries. Construction planning started in July 2014 after the formal signature of an agreement between the main institutions involved. == Overview == LLAMA is a joint project between Argentinian and Brazilian Astronomers to build and operate a radio telescope at submillimeter wavelengths, that can work in stand alone mode or join a Very Long Baseline Interferometry (VLBI) network. The main scientific institutions involved in the project are the Argentine Institute of Radio Astronomy (IAR), and the Núcleo para o Apoio da Rádio Astronomia (NARA), from the Universidade de São Paulo (Brazil). The


id: large-latin-american-millimeter-array-20260505-1
file: data/en.wikipedia.org/wiki/Large_Latin_American_Millimeter_Array-1.md
category: reference
title: Large Latin American Millimeter Array
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Large_Latin_American_Millimeter_Array
date_saved: 2026-05-05T09:41:08.739089+00:00
instance: kb-cron
parent: large-latin-american-millimeter-array-20260505-0
summary:
=== Galactic and Intergalactic interstellar medium === Continuum radiation from extragalactic cold dust. Molecular material in the direction of different stellar objects. Intergalactic Medium using the detection of molecular absorption lines in the direction of quasars. Cosmic background radiation. === Galaxies === Search for CO in galaxies with high redshift. Molecular abundance. Active Galactic Nuclei (AGN). Variation of the fundamental constants by the observation of gravitational lensing. High redshifts of regions with very high rate of star formation. Proto-clusters of galaxies. Space-time distortion produced by massive black holes. === High energies === == Optics, Receivers == The Nasmyth optics will allow the installation of up to as six different heterodyne receivers. There is a consensus for these receivers to use the same spectral bands as ALMA. With this scheme the Nasmyth cabins will allocate receivers for the bands It is intended to install a bolometer multi-wavelength camera at the Cassegrain focus, or possibly a camera plus a small heterodyne array. == See also == Atacama Large Millimeter Array, the biggest millimeter array ever built. Atacama Pathfinder Experiment (APEX), single dish sub-millimetre telescope built on a modified ALMA prototype antenna Atacama Submillimeter Telescope Experiment CARMA a sensitive millimetre-wave array operated by


id: lunar-surface-electromagnetics-experiment-20260505-0
file: data/en.wikipedia.org/wiki/Lunar_Surface_Electromagnetics_Experiment-0.md
category: reference
title: Lunar Surface Electromagnetics Experiment
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lunar_Surface_Electromagnetics_Experiment
date_saved: 2026-05-05T09:41:09.895647+00:00
instance: kb-cron
parent: lunar-surface-electromagnetics-experiment-20260505-0
summary:
The Lunar Surface Electromagnetics Experiment (LuSEE-Night) is a planned robotic radio telescope observatory designed to land and function on the far side of Earth's Moon. The project is under development by the U.S. Department of Energy Brookhaven National Laboratory, the DOE Office of Science, UC Berkeley’s Space Sciences Laboratory and the National Aeronautics and Space Administration. If successfully deployed and activated, LuSEE-Night will attempt measurements of an early period of the history of the Universe that occurred relatively soon after the Big Bang, referred to as the Dark Ages of the Universe, which predates the formation of luminous stars and galaxies. The instrument is planned to be landed on the lunar far side as soon as 2026 aboard the Blue Ghost Mission 2 lunar lander. LuSEE-Night, not to be confused with a companion lander planned for lunar landing in 2024 named LuSEE-Lite, is to be delivered to the lunar far side by Commercial Lunar Payload Services (CLPS). == See also == Netherlands–China Low-Frequency Explorer (NCLE) Chronology of the universe Large Aperture Experiment to Detect the Dark Ages Lunar Crater Radio Telescope == References == == External links == March 2023 NASA LuSEE-Night statement


