# kb

id: spectroheliograph-20260505-0
file: data/en.wikipedia.org/wiki/Spectroheliograph-0.md
category: reference
title: Spectroheliograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroheliograph
date_saved: 2026-05-05T09:42:08.444385+00:00
instance: kb-cron
parent: spectroheliograph-20260505-0
summary:
The spectroheliograph is an instrument used in astronomy which captures a photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a spectral wavelength of one of the chemical elements present in the Sun. It was developed independently by George Ellery Hale and Henri-Alexandre Deslandres in the 1890s and further refined in 1932 by Robert R. McMath to take motion pictures. The instrument comprises a prism or diffraction grating and a narrow slit that passes a single wavelength (a monochromator). The light is focused onto a photographic medium and the slit is moved across the disk of the Sun to form a complete image. It is now possible to make a filter that transmits a narrow band of wavelengths which produces a similar image, but spectroheliographs remain in use. == See also == Spectrohelioscope Helioscope Heliometer == References == == External links == "Spectroheliograph" . Encyclopædia Britannica. Vol. 25 (11th ed.). 1911. An amateur-made spectroheliograph


id: spectrohelioscope-20260505-0
file: data/en.wikipedia.org/wiki/Spectrohelioscope-0.md
category: reference
title: Spectrohelioscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectrohelioscope
date_saved: 2026-05-05T09:42:09.572048+00:00
instance: kb-cron
parent: spectrohelioscope-20260505-0
summary:
A spectrohelioscope is a type of solar telescope designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength of light. The name comes from Latin- and Greek-based words: "Spectro," referring to the optical spectrum, "helio," referring to the Sun, and "scope," as in telescope. The basic spectrohelioscope is a complex machine that uses a spectroscope to scan the surface of the Sun. The image from the objective lens is focused on a narrow slit revealing only a thin portion of the Sun's surface. The light is then passed through a prism or diffraction grating to spread the light into a spectrum. The spectrum is then focused on another slit that allows only a narrow part of the spectrum (the desired wavelength of light for viewing) to pass. The light is finally focused on an eyepiece so the surface of the Sun can be seen. The view, however, would be only a narrow strip of the Sun's surface. The slits are moved in unison to scan across the whole surface of the Sun giving a full image. Independently nodding mirrors can be used instead of moving slits to produce the same scan: the


id: spex-astronomy-20260505-0
file: data/en.wikipedia.org/wiki/SPEX_(astronomy)-0.md
category: reference
title: SPEX (astronomy)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SPEX_(astronomy)
date_saved: 2026-05-05T09:42:10.747902+00:00
instance: kb-cron
parent: spex-astronomy-20260505-0
summary:
The SPEX (Spectropolarimeter for Planetary Exploration) is a single-channel, high-precision polarimeter for the characterization of planetary atmospheres. It is intended for planetary science missions, but it could, with minor modifications, also be used for Earth observation by a microsatellite, such as the Dutch FAST-D project. == References == === Cross-reference === === Sources used === == Further reading == Rietjens, J.H.H.; Snik, F.; Stam, D.M.; Smit, J.M.; van Harten, G.; Keller, C.U.; Verlaan, A.L.; Laan, E.C.; ter Horst, R.; Navarro, R.; Wielinga, K.; Moon, S.G.; Voors, R. (2010). SPEX: Spectropolarimeter for Planetary EXploration (PDF). International Conference on Space Optics 4–8 October 2010 Rhodes, Greece. Voors, Robert; Moon, Scott G.; Hannemann, Sandro; Rietjens, Jeroen H. H.; van Harten, Gerard; Snik, Frans; Smit, Martijn; Stam, Daphne M.; Keller, Christoph U.; Laan, Erik C.; Verlaan, Adrianus L.; Vliegenthart, Willem A.; Ter Horst, Rik; Navarro, Ramón; Wielenga, Klaas (2011). Meynart, Roland; Neeck, Steven P.; Shimoda, Haruhisa (eds.). Spectropolarimeter for planetary exploration (SPEX): performance measurements with a prototype (PDF). Proceedings of the SPIE: Sensors, Systems, and Next-Generation Satellites XV. Vol. 8176. pp. 81760D–81760D–12. doi:10.1117/12.897706. van Harten, Gerard; Snik, Frans; Rietjens, Jeroen H. H.; Smit, J. Martijn; de Boer, Jozua; Diamantopoulou, Renia; Hasekamp, Otto P.; Stam,


id: spider-polarimeter-20260505-0
file: data/en.wikipedia.org/wiki/Spider_(polarimeter)-0.md
category: reference
title: Spider (polarimeter)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spider_(polarimeter)
date_saved: 2026-05-05T09:42:11.947346+00:00
instance: kb-cron
parent: spider-polarimeter-20260505-0
summary:
Spider is a balloon-borne experiment designed to search for primordial gravitational waves imprinted on the cosmic microwave background (CMB). Measuring the strength of this signal puts limits on inflationary theory. The Spider instrument consists of six half degree-resolution telescopes cooled to liquid Helium temperature (4 K) which observe at frequencies of 100 GHz, 150 GHz, and 280 GHz (corresponding to wavelengths of 3 mm, 2 mm, and 1.1 mm). Each telescope is coupled to a polarisation-sensitive transition-edge bolometer (TES) array cooled to 300 mK. Spider was the first instrument to successfully demonstrate time-domain multiplexed TES detectors in a space-like environment. At the time of the first flight over Antarctica in 2015, Spider was the most sensitive microwave instrument ever made. The primary science goals include: characterization of the curl-free component of the CMB polarization on the largest scales searching for the signature of inflationary gravitational waves in the CMB polarization characterization of the polarization properties of the emission from our own Milky Way Galaxy The first balloon flight of the experiment launched in January 2015 from McMurdo Station, Antarctica, with support from NASA's Columbia Scientific Balloon Facility. This Long Duration Balloon flight lasted for about 17 days, mapping about 10%


id: stonyhurst-disks-20260505-0
file: data/en.wikipedia.org/wiki/Stonyhurst_disks-0.md
category: reference
title: Stonyhurst disks
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Stonyhurst_disks
date_saved: 2026-05-05T09:42:13.135473+00:00
instance: kb-cron
parent: stonyhurst-disks-20260505-0
summary:
A Stonyhurst disk is a transparent circular grid with lines of solar longitude and latitude that can be overlaid on a solar image to reference the positions of sunspots. This system was originally developed at the Stonyhurst College observatory. == References ==


id: supernova-early-warning-system-20260505-0
file: data/en.wikipedia.org/wiki/SuperNova_Early_Warning_System-0.md
category: reference
title: SuperNova Early Warning System
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SuperNova_Early_Warning_System
date_saved: 2026-05-05T09:42:14.343469+00:00
instance: kb-cron
parent: supernova-early-warning-system-20260505-0
summary:
The SuperNova Early Warning System (SNEWS) is a network of neutrino detectors designed to give early warning to astronomers in the event of a supernova in the Milky Way, our home galaxy, or in a nearby galaxy such as the Large Magellanic Cloud. SNEWS has been operating since 2005. As of March 2021, it has not issued any supernova alerts. This is unsurprising, as supernovae appear to be rare: the most recent known supernova remnant in the Milky Way was around the turn of the 20th century, and the most recent Milky Way supernova confirmed to have been observed was Kepler's Supernova in 1604. == SNEWS 2.0 == In June 2019 a "SNEWS 2.0" workshop was held at Laurentian University of Sudbury in Canada, focused on plans for an update of SNEWS. As the result, an upgraded system was devised under the name "SNEWS 2.0". == Neutrino detection == Powerful bursts of electron neutrinos (νe) with typical energies of the order of 10 MeV and duration of the order of 10 seconds are produced in the core of a red giant star as it collapses on itself via the "neutronization" reaction, i.e. fusion of protons and electrons into neutrons and


id: sutton-armillary-20260505-0
file: data/en.wikipedia.org/wiki/Sutton_armillary-0.md
category: reference
title: Sutton armillary
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Sutton_armillary
date_saved: 2026-05-05T09:42:15.631352+00:00
instance: kb-cron
parent: sutton-armillary-20260505-0
summary:
The Millennium Dial Armillary is one of six pieces of public art located in the town centre of Sutton in Greater London, England. The others include the Sutton heritage mosaic, the Sutton twin towns mural and the Messenger statue. The armillary was dedicated to the town in 2000 by the Rotary Club, and is in the form of a historical timepiece. It serves three purposes: firstly, simply to tell the time; secondly, to commemorate time through various inscriptions including the Rotary motto "Service Above Self" and distances to nearby areas such as Kingston upon Thames; and thirdly, to commemorate the work which the Rotary Club has done. == Inscription == The inscription on the plinth reads as follows: "Service Above Self" Rotary Armillary This Armillary was presented to the people of the London Borough of Sutton in grateful thanks for their generosity in supporting Rotary Charities and to mark the new Millennium. The Rotary Club of Cheam has joined with the Rotary Clubs of Carshalton, Carshalton Beeches, Sutton, Sutton Nonsuch and Wallington. December 2000 The Project was made possible by the following Sponsors: Securicor plc. Holiday Inn Sutton London. The Crown Agents. South Sutton Neighbourhood Association. Sutton & Cheam Society.


id: swiss-1-2-metre-leonhard-euler-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Swiss_1.2-metre_Leonhard_Euler_Telescope-0.md
category: reference
title: Swiss 1.2-metre Leonhard Euler Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Swiss_1.2-metre_Leonhard_Euler_Telescope
date_saved: 2026-05-05T09:42:16.835986+00:00
instance: kb-cron
parent: swiss-1-2-metre-leonhard-euler-telescope-20260505-0
summary:
Leonhard Euler Telescope, or the Swiss EULER Telescope, is a national, fully automatic 1.2-metre (47 in) reflecting telescope, built and operated by the Geneva Observatory. It is located at an altitude of 2,375 m (7,792 ft) at ESO's La Silla Observatory site in the Chilean Norte Chico region, about 460 kilometers north of Santiago de Chile. The telescope, which saw its first light on 12 April 1998, is named after Swiss mathematician Leonhard Paul Euler. The Euler telescope uses the CORALIE instrument to search for exoplanets. In addition, the telescope uses the multi-purpose EulerCam (ecam), a high precision photometry instrument, and a smaller, piggyback mounted telescope, called "Pisco". Its first discovery was a planet in orbit around Gliese 86, determined to be a hot Jupiter with an orbital period of only 15.8 earth days and about four times the mass of Jupiter. Since then, many other exoplanets have been discovered or examined in follow-up observations. Together with the Mercator Telescope, Euler was part of the Southern Sky extrasolar Planet search Programme, which has discovered numerous extrasolar planets. It has also been frequently employed for follow-up characterization to determine the mass of exoplanets discovered by the Wide Angle Search for Planets,


id: telecompressor-20260505-0
file: data/en.wikipedia.org/wiki/Telecompressor-0.md
category: reference
title: Telecompressor
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telecompressor
date_saved: 2026-05-05T09:42:17.974207+00:00
instance: kb-cron
parent: telecompressor-20260505-0
summary:
A telecompressor or focal reducer is an optical element used to reduce focal length, increase lens speed, and in some instances improve optical transfer function (OTF) performance. It is also widely known under the name “Speed Booster”, which is the commercial name of a line of telecompressors by the manufacturer Metabones. Popular applications include photography, videography, and astrophotography. In astrophotography, these qualities are most desirable when taking pictures of nearby large objects, such as nebulae. The effects and uses of the telecompressor are largely opposite to those of the teleconverter or Barlow lens. A combined system of a lens and a focal reducer has smaller back focus than the lens alone; this places restrictions on lenses and cameras that focal reducer might be used with. Lens adapters that include telecompressors are useful with digital mirrorless cameras. By combining a telecompressor within a lens adapter, mirrorless cameras can use the lenses of both digital single-lens reflex cameras (DSLRs) and film-based SLR (Single-lens reflex cameras). == Calculating focal reduction == For a refractor telescope or simple camera lens, the new effective focal length fn is given by: f n = f o ( 1 − d f r ) , {\displaystyle {f_{n}}={f_{o}}\left(1-{\frac


id: telescope-20260505-0
file: data/en.wikipedia.org/wiki/Telescope-0.md
category: reference
title: Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telescope
date_saved: 2026-05-05T09:42:19.149708+00:00
instance: kb-cron
parent: telescope-20260505-0
summary:
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally, it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The first known practical telescopes were refracting telescopes with glass lenses and were invented in the Netherlands at the beginning of the 17th century. They were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s. == Etymology == The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei. In the Starry Messenger, Galileo had used the Latin term perspicillum. The root of the word is from the Ancient


id: telescope-20260505-1
file: data/en.wikipedia.org/wiki/Telescope-1.md
category: reference
title: Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Telescope
date_saved: 2026-05-05T09:42:19.149708+00:00
instance: kb-cron
parent: telescope-20260505-0
summary:
=== Radio and submillimeter === Radio telescopes are directional radio antennas that typically employ a large dish to collect radio waves. The dishes are sometimes constructed of a conductive wire mesh whose openings are smaller than the wavelength being observed. Unlike an optical telescope, which produces a magnified image of the patch of sky being observed, a traditional radio telescope dish contains a single receiver and records a single time-varying signal characteristic of the observed region; this signal may be sampled at various frequencies. In some newer radio telescope designs, a single dish contains an array of several receivers; this is known as a focal-plane array. By collecting and correlating signals simultaneously received by several dishes, high-resolution images can be computed. Such multi-dish arrays are known as astronomical interferometers and the technique is called aperture synthesis. The 'virtual' apertures of these arrays are similar in size to the distance between the telescopes. As of 2005, the record array size is many times the diameter of the Earth – using space-based very-long-baseline interferometry (VLBI) telescopes such as the Japanese HALCA (Highly Advanced Laboratory for Communications and Astronomy) VSOP (VLBI Space Observatory Program) satellite. Aperture synthesis is now also being applied to


id: tellurion-20260505-0
file: data/en.wikipedia.org/wiki/Tellurion-0.md
category: reference
title: Tellurion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tellurion
date_saved: 2026-05-05T09:42:20.330771+00:00
instance: kb-cron
parent: tellurion-20260505-0
summary:
A tellurion (also spelled tellurian, tellurium, and yet another name is loxocosm), is a clock, typically of French or Swiss origin, surmounted by a mechanism that depicts how day, night, and the seasons are caused by the rotation and orientation of Earth on its axis and its orbit around the Sun. The clock normally also displays the phase of the Moon and the four-year (perpetual) calendar. It is related to the orrery, which illustrates the relative positions and motions of the planets and moons in the Solar System in a heliocentric model. The word tellurion derives from the Latin tellus, meaning "earth". == See also == Astronomical clock Solar System models == References == == External links ==


id: torquetum-20260505-0
file: data/en.wikipedia.org/wiki/Torquetum-0.md
category: reference
title: Torquetum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Torquetum
date_saved: 2026-05-05T09:42:21.555663+00:00
instance: kb-cron
parent: torquetum-20260505-0
summary:
The torquetum or turquet is a medieval astronomical instrument for taking and converting measurements made in three sets of coordinates: horizon, equatorial, and ecliptic. It is characterised by R. P. Lorch as a combination of Ptolemy's astrolabon (Greek: αστρολάβον) and the plane astrolabe. In a sense, the torquetum is an analog computer. == Invention == The origins of the torquetum are unclear. Its invention has been credited to multiple figures, including Jabir ibn Aflah, Bernard of Verdun and Franco of Poland. In 1469, Regiomontanus credited an 11th-century Arab astronomer from Seville, Jabir ibn Aflah. Later, in 1598, Tycho Brahe speculated that it was a 12th-century creation of "Arabians or Chaldeans." Eventually, early 20th-century German historians shifted the attribution to the "Turks." Jabir ibn Aflah of Al-Andalus in the early 12th century has been assumed by several historians to be the inventor of the torquetum, based on a similar instrument he described in his Islah Almajisti. However, while his device is similar in function, it has not been identified as a torquetum, but evidence suggests it inspired the torquetum. According to Joseph Needham, a simplified version of the torquetum was among the instruments documented at the imperial Chinese observatory of the


id: torquetum-20260505-1
file: data/en.wikipedia.org/wiki/Torquetum-1.md
category: reference
title: Torquetum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Torquetum
date_saved: 2026-05-05T09:42:21.555663+00:00
instance: kb-cron
parent: torquetum-20260505-0
summary:
== Components == The torquetum is a complex medieval analog computer that measures three sets of astronomical coordinates: the horizon, equatorial, and ecliptic. One of the defining attributes of the torquetum is its ability to interconvert between these three sets of coordinate dimensions without the use of calculations, as well as to demonstrate the relationship between the same coordinate sets. However, it is a device that requires a thorough understanding of the components and how they work together to make relative positional measurements of certain celestial objects. The anatomy of the torquetum involves many different components, which can be grouped into subdivisions of the torquetum structure, those being: the base, the midframe, and the upperframe. The base starts with the tabula orizontis, which is the bottommost rectangular piece in contact with the ground, and this component represents the horizon of the Earth, relative to the point of measurement. Hinged to the tabula orizontis is a similarly shaped component, the tabula equinoctialis, which represents the latitude of the Earth. This piece can rotate up to 90 degrees, coinciding with the latitudinal lines of the Earth from the equator to the poles. This angle of rotation is created by the stylus, which


id: triquetrum-astronomy-20260505-0
file: data/en.wikipedia.org/wiki/Triquetrum_(astronomy)-0.md
category: reference
title: Triquetrum (astronomy)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Triquetrum_(astronomy)
date_saved: 2026-05-05T09:42:22.798000+00:00
instance: kb-cron
parent: triquetrum-astronomy-20260505-0
summary:
The triquetrum (derived from the Latin tri- 'three' and quetrum 'cornered') was the medieval name for an ancient astronomical instrument first described by Ptolemy (c. 90 – c. 168) in the Almagest (V. 12). Also known as Parallactic Rulers, it was used for determining altitudes of heavenly bodies. Ptolemy calls it a "parallactic instrument" and seems to have used it to determine the zenith distance and parallax of the Moon. == Design == The triquetrum performed the same function as the quadrant and was devised to overcome the difficulty of graduating arcs and circles. It consisted of a vertical post with a graduated scale and two pivoted arms hinged at the top and bottom, the upper arm carrying sights. The two arms were joined so that their ends could slide. As a person sighted along the upper arm, the lower one changed its angle. By reading the position of the lower rod, in combination with the vertical length, the zenith distance (or, alternatively, the altitude) of a celestial object could be calculated. == Use == The triquetrum was one of the most popular astronomical instruments until the invention of the telescope, it could measure angles with a better precision than


id: verona-astrolabe-20260505-0
file: data/en.wikipedia.org/wiki/Verona_astrolabe-0.md
category: reference
title: Verona astrolabe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Verona_astrolabe
date_saved: 2026-05-05T09:42:24.032256+00:00
instance: kb-cron
parent: verona-astrolabe-20260505-0
summary:
The Verona astrolabe is an archaeological discovery unearthed in the vaults of a museum in Verona, Italy. Dating back to the eleventh century, this Islamic astrolabe is one of the oldest examples of its kind and is among the few known to exist worldwide. It appears to have been employed by Muslim, Jewish, and Christian communities spanning Spain, North Africa, and Italy over several centuries. Described by historian Tom Almeroth-Williams of the University of Cambridge as the "world's first smartphone," the astrolabe served as a portable astronomical instrument capable of diverse functionalities. It provided users with a two-dimensional representation of the universe, enabling the plotting of star positions, calculation of time and distances, and even the development of horoscopes. Initially doubted to be authentic, the Verona Astrolabe was authenticated as an eleventh-century artifact by Dr. Federica Gigante of Cambridge University's History Faculty. Her analysis, published in the journal Nuncius, confirmed its origins in Al-Andalus, the Muslim-ruled region of Spain during the medieval period. The astrolabe bears Hebrew inscriptions alongside Arabic, indicating its circulation within the Jewish diaspora community in Italy, where Hebrew was used in place of Arabic. == References ==


id: visible-multi-object-spectrograph-20260505-0
file: data/en.wikipedia.org/wiki/Visible_Multi_Object_Spectrograph-0.md
category: reference
title: Visible Multi Object Spectrograph
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Visible_Multi_Object_Spectrograph
date_saved: 2026-05-05T09:42:25.209834+00:00
instance: kb-cron
parent: visible-multi-object-spectrograph-20260505-0
summary:
The Visible Multi-Object Spectrograph (VIMOS) is a wide field imager and a multi-object spectrograph installed at the European Southern Observatory's Very Large Telescope (VLT), in Chile. The instrument used for deep astronomical surveys delivers visible images and spectra of up to 1,000 galaxies at a time. VIMOS images four rectangular areas of the sky, 7 by 8 arcminutes each, with gaps of 2 arcminutes between them. Its principal investigator was Olivier Le Fèvre. The Franco-Italian instrument operates in the visible part of the spectrum from 360 to 1000 nanometers (nm). In the conceptual design phase, the multi-object spectrograph then called VIRMOS included an additional instrument, NIMOS, operating in the near-infrared spectrum of 1100–1800 nm. Operating in the three different observation modes, direct imaging, multi-slit spectroscopy, and integral field spectroscopy, the main objective of the instrument is to study the early universe through massive redshift surveys, such as the VIMOS-VLT Deep Survey. VIMOS saw its first light on 26 February 2002, and has since been mounted on the Nasmyth B focus of VLT's Melipal unit telescope (UT3). It was retired in 2018 to make space for the return of CRIRES+. == Gallery == == See also == List of instruments at


id: volvelle-20260505-0
file: data/en.wikipedia.org/wiki/Volvelle-0.md
category: reference
title: Volvelle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Volvelle
date_saved: 2026-05-05T09:42:26.363356+00:00
instance: kb-cron
parent: volvelle-20260505-0
summary:
A volvelle or wheel chart is a type of slide chart, a paper construction with rotating parts. It is considered an early example of a paper analog computer. Volvelles have been produced to accommodate organization and calculation in many diverse subjects. Early examples of volvelles are found in the pages of astronomy books. A moveable device for working out the position of the sun and moon in the zodiac is known as a volvella. == 20th century == In the twentieth century, the volvelle had many diverse uses. In Reinventing the Wheel, author Jessica Helfand introduces twentieth-century volvelles with this: The twentieth century saw a robust growth in the design, manufacture, and production of a new generation of independent, free-standing volvelles. Categorically, they not only represent an unusually eclectic set of uses, but demonstrate, too, a remarkable range of stylistic, compositional, mechanical, informational, and kinetic conceits. There are volvelles that arrange their data peripherally, centrifugally, and radially; volvelles that use multiple concentric circles with pointers; and volvelles that benefit from the generous use of the die-cut, a particular technological hallmark of modern printing manufacture. Twentieth-century volvelles—often referred to as wheel charts—offer everything from inventory control to color calibration, mileage metering


id: warkworth-radio-astronomical-observatory-20260505-0
file: data/en.wikipedia.org/wiki/Warkworth_Radio_Astronomical_Observatory-0.md
category: reference
title: Warkworth Radio Astronomical Observatory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Warkworth_Radio_Astronomical_Observatory
date_saved: 2026-05-05T09:42:27.517774+00:00
instance: kb-cron
parent: warkworth-radio-astronomical-observatory-20260505-0
summary:
The Warkworth Radio Astronomical Observatory is a radio telescope observatory, located just south of Warkworth, New Zealand, about 50 km north of the Auckland CBD. It was established by the Institute for Radio Astronomy and Space Research, Auckland University of Technology. The WARK12M 12m Radio Telescope was constructed in 2008. In 2010, a licence to operate the Telecom New Zealand 30m dish was granted, which led to the commissioning of the WARK30M 30m Radio Telescope. The first observations made in conjunction with the Australian Long Baseline Array took place in 2011. The observatory was purchased by Space Operations New Zealand Limited (SpaceOps NZ) in July 2023 after the university decided to close the facility. Because of its wider ambit, the facility is now called the Warkworth Space Centre. == History == The Warkworth Space Centre is on land that was first developed for long-range telecommunications, operated by the New Zealand Post Office and opening on 17 July 1971. The station, primarily connecting to fourth generation Intelsat satellites, was used for satellite telephone circuits and television, including the broadcast of the 1974 British Commonwealth Games, held in Christchurch. The shallow valley site was chosen as it was sheltered from winds and


id: warkworth-radio-telescope-20260505-0
file: data/en.wikipedia.org/wiki/Warkworth_Radio_Telescope-0.md
category: reference
title: Warkworth Radio Telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Warkworth_Radio_Telescope
date_saved: 2026-05-05T09:42:28.752570+00:00
instance: kb-cron
parent: warkworth-radio-telescope-20260505-0
summary:
The Warkworth 12m Radio Telescope is a radio telescope at the Warkworth Radio Astronomical Observatory, located just south of Warkworth, New Zealand, about 50 km north of the Auckland CBD. It is operated by the Institute of Radio Astronomy and Space Research of Auckland University of Technology and was constructed in 2008. == Technical information == The 12m diameter antenna was designed and constructed by COBHAM Satcom. The antenna is a fully steerable dual shaped Cassegrain with a main dish diameter of 12.1m and a secondary reflector diameter of 1.8m. The focal Length is 4.538m. The surface precision is 0.35mm (RMS) and the pointing accuracy is 18 inches. It operates in the L-Band, S-Band and X-Band with dual polarisation S and X-band feeds from COBHAM with room temperature receivers. The receiver systems cover 2.2 to 2.4 GHz at S-band and 8.1 to 9.1 GHz at X-band. It is mounted alt-azimuth and has slewing rates of 5 deg/s in azimuth and 1.25 deg/s in elevation, and acceleration of 1.3 deg/s/s. == Research activity == In 2010 this dish was used for several very-long-baseline interferometry(VLBI) observations in conjunction with the Australian Long Baseline Array. From 2011 it was a part of the


id: double-violin-20260505-0
file: data/en.wikipedia.org/wiki/Double_violin-0.md
category: reference
title: Double violin
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Double_violin
date_saved: 2026-05-05T09:42:31.335988+00:00
instance: kb-cron
parent: double-violin-20260505-0
summary:
The Double Violin is a ten-string, stereophonic double-necked electric violin invented by violinist L. Shankar. It is also referred to as the LSD or L. Shankar's Double Violin. == Description == The double violin is capable of replicating a full orchestra's effect with the lower neck covering the double bass and cello range, and the upper neck generating treble sounds; the violin and viola. In addition to providing a wide range of five and a half octaves, playing on one neck produces a sympathetic resonance effect on the other. The horizontal rib can be positioned beneath the chin or supported against the chest (Indian style) while playing. Due to the instrument's greater angle, the bowing was different and Shankar incorporated new techniques including playing on both necks simultaneously. The concept for the double violin originated in 1978, after producing his album by Zappa Records where Shankar had to overdub a wide range of string instruments as he was unable to find session musicians who could render the Indian ornaments and styles he wanted. He made a prototype with cardboard and spent about a year and a half improving the design. To date, Shankar has commissioned four different versions of the


id: electricity-meter-20260505-0
file: data/en.wikipedia.org/wiki/Electricity_meter-0.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
An electricity meter, electric meter, electrical meter, energy meter, kilowatt-hour meter, or power meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device over a time interval. Electric utilities use electric meters installed at customers' premises for billing and monitoring purposes. They are typically calibrated in billing units, the most common one being the kilowatt hour (kWh). They are usually read once each billing period. When energy savings during certain periods are desired, some meters may measure demand, the maximum use of power in some interval. "Time of day" metering allows electric rates to be changed during a day, to record usage during peak high-cost periods and off-peak, lower-cost, periods. Also, in some areas meters have relays for demand response load shedding during peak load periods. == History == The earliest commercial uses of electric energy, in the 1880s, had easily predictable usage; billing was based on the number of lamps or motors installed in a building. However, as usage spread, and especially with the invention of pluggable appliances, it also became more variable, and the electric utilities sought a means to bill customers based on actual rather


id: electricity-meter-20260505-1
file: data/en.wikipedia.org/wiki/Electricity_meter-1.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
The most common unit of measurement on the electricity meter is the kilowatt hour [kWh], which is equal to the amount of energy used by a load of one kilowatt over a period of one hour, or 3,600,000 joules. Some electricity companies use the SI megajoule instead. Demand is normally measured in watts, but averaged over a period, most often a quarter- or half-hour. Reactive power is measured in "thousands of volt-ampere reactive-hours", (kvarh). By convention, a "lagging" or inductive load, such as a motor, will have positive reactive power. A "leading", or capacitive load, will have negative reactive power. Volt-amperes measures all power passed through a distribution network, including reactive and actual. This is equal to the product of root-mean-square volts and amperes. Distortion of the electric current by loads is measured in several ways. Power factor is the ratio of resistive (or real) power to volt-amperes. A capacitive load has a leading power factor, and an inductive load has a lagging power factor. A purely resistive load (such as a filament lamp, heater or kettle) exhibits a power factor of 1. Current harmonics are a measure of distortion of the wave form. For example, electronic loads such as


id: electricity-meter-20260505-2
file: data/en.wikipedia.org/wiki/Electricity_meter-2.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
t = time in seconds taken by the disc to complete one revolution, P = power in watts. For example, if Kh = 7.2 as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one. Most domestic electricity meters must be read manually, whether by a representative of the power company or by the customer. Where the customer reads the meter, the reading may be supplied to the power company by telephone, post or over the internet. The electricity company will normally require a visit by a company representative at least annually in order to verify customer-supplied readings and to make a basic safety check of the meter. In an induction type meter, creep is a phenomenon that can adversely affect accuracy, that occurs when the meter disc rotates continuously with potential applied and the load terminals open circuited. A test for error due to creep is called a creep test. Two standards govern meter accuracy, ANSI C12.20 for North America and IEC 62053. === Electronic === Electronic meters display the energy used on an LCD


id: electricity-meter-20260505-3
file: data/en.wikipedia.org/wiki/Electricity_meter-3.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
EN 62053-31 (formerly DIN 43864) defines the S0 interface, which is a galvanically isolated open collector output. Voltage and current are limited to 27 V and 27 mA, respectively. Each metered amount of electrical energy produces one impulse with a length of 32-100 ms. The meter constant (pulses per kWh) is programmable on some meters, but often fixed to 1000-10000 pulses per kWh. Other meters implement a similar pulse interface, but with an infrared LED instead of an electrical connection. The interface is also used on other kinds of meters, like water meters. Many meters designed for semi-automated reading have a serial port that communicates by infrared LED through the faceplate of the meter. In some multi-unit buildings, a similar protocol is used, but in a wired bus using a serial current loop to connect all the meters to a single plug. The plug is often near a more easily accessible point. In the European Union, the most common infrared and protocol is "FLAG", a simplified subset of mode C of IEC 61107. In the United States and Canada, the favored infrared protocol is ANSI C12.18. Some industrial meters use protocols for programmable logic controllers, like Modbus or DNP3. One


id: electricity-meter-20260505-4
file: data/en.wikipedia.org/wiki/Electricity_meter-4.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
Radio-activated switching is common in the UK, with a nightly data signal sent within the longwave carrier of BBC Radio 4, 198 kHz. The time of off-peak charging is usually seven hours between midnight and 7:00am GMT/BST, and this is designed to power storage heaters and immersion heaters. In the UK, such tariffs are typically branded Economy 7, White Meter or Dual-Rate. The popularity of such tariffs has declined in recent years, at least in the domestic market, because of the (perceived or real) deficiencies of storage heaters and the comparatively much lower cost of natural gas per kWh (typically a factor of 3-5 times lower). Nevertheless, a sizeable number of properties do not have the option of gas, with many in rural areas being outside the gas supply network, and others being expensive upfront to upgrade to a radiator system. An Economy 10 meter is also available, which gives 10 hours of cheap off-peak electricity spread out over three timeslots throughout a 24-hour period. This allows multiple top-up boosts to storage heaters, or a good spread of times to run a wet electric heating system on a cheaper electricity rate. Most meters using Economy 7 switch the entire electricity


id: electricity-meter-20260505-5
file: data/en.wikipedia.org/wiki/Electricity_meter-5.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
=== Time of day metering === Time of Day metering (TOD), also known as Time of Usage (TOU) or Seasonal Time of Day (SToD), metering involves dividing the day, month and year into tariff slots and with higher rates at peak load periods and low tariff rates at off-peak load periods. While this can be used to automatically control usage on the part of the customer (resulting in automatic load control), it is often simply the customer's responsibility to control his own usage or pay accordingly (voluntary load control). This also allows the utilities to plan their transmission infrastructure appropriately. See also Demand-side Management (DSM). TOD metering normally splits rates into an arrangement of multiple segments including on-peak, off-peak, mid-peak or shoulder, and critical peak. A typical arrangement is a peak occurring during the day (non-holiday days only), such as from 1 pm to 9 pm Monday through Friday during the summer and from 6:30 am to 12 noon and 5 pm to 9 pm during the winter. More complex arrangements include the use of critical peaks that occur during high demand periods. The times of peak demand/cost will vary in different markets around the world. Large commercial users can


id: electricity-meter-20260505-6
file: data/en.wikipedia.org/wiki/Electricity_meter-6.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
=== Customer drop and metering equation === Since electrical standards vary in different regions, "customer drops" from the grid to the customer also vary depending on the standards and the type of installation. There are several common types of connections between a grid and a customer. Each type has a different metering equation. Blondel's theorem states that for any system with N current-carrying conductors, that N-1 measuring elements are sufficient to measure electrical energy. This indicates that different metering is needed, for example, for a three-phase three-wire system than for a three-phase four-wire (with neutral) system. In Europe, Asia, Africa and most other locations, single phase is common for residential and small commercial customers. Single phase distribution is less-expensive, because one set of transformers in a substation normally serve a large area with relatively high voltages (usually 230 V) and no local transformers. These have a simple metering equation: Watts = volts x amps, with volts measured from the neutral to the phase wire. In the United States, Canada, and parts of Central and South America similar customers are normally served by three-wire single phase. Three-wire single-phase requires local transformers, as few as one per ten residences, but provides lower,


id: electricity-meter-20260505-7
file: data/en.wikipedia.org/wiki/Electricity_meter-7.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
== Tampering and security == Meters can be manipulated to make them under-register, effectively allowing power use without paying for it. Power companies often install remote-reporting meters specifically to enable remote detection of tampering, and specifically to discover energy theft. The change to smart power meters is useful to stop energy theft. When tampering is detected, the normal tactic, legal in most areas of the United States, is to switch the subscriber to a "tampering" tariff charged at the meter's maximum designed current. At US$0.095/kWh, a standard residential 50 A meter causes a legally collectible charge of about US$5,000.00 per month. Meter readers are trained to spot signs of tampering, and with crude mechanical meters, the maximum rate may be charged each billing period until the tamper is removed, or the service is disconnected. A common method of tampering on mechanical disk meters is to attach magnets to the outside of the meter. Strong magnets saturate the magnetic fields in the meter so that the motor portion of a mechanical meter does not operate. Lower power magnets can add to the drag resistance of the internal disk resistance magnets. Magnets can also saturate current transformers or power-supply transformers in electronic


id: electricity-meter-20260505-8
file: data/en.wikipedia.org/wiki/Electricity_meter-8.md
category: reference
title: Electricity meter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electricity_meter
date_saved: 2026-05-05T09:42:32.585250+00:00
instance: kb-cron
parent: electricity-meter-20260505-0
summary:
== Regulation and legislation == Following the deregulation of electricity supply markets in many countries, the company responsible for an electricity meter may not be obvious. Depending on the arrangements in place, the meter may be the property of the meter Operator, electricity distributor, the retailer or for some large users of electricity the meter may belong to the customer. The company responsible for reading the meter may not always be the company which owns it. Meter reading is now sometimes subcontracted and in some areas the same person may read gas, water and electricity meters at the same time. The introduction of advanced meters in residential areas has produced additional privacy issues that may affect ordinary customers. These meters are often capable of recording energy usage every 15, 30 or 60 minutes. Some meters have one or two IR LEDs on the front: one used for testing and which acts as the equivalent of the timing mark on the older mechanical meters and the other as part of a two-way IR communications port for reading / programming the meter. These IR LEDs are visible with some night vision viewers and certain video cameras that are capable of sensing IR


id: electrophorus-20260505-0
file: data/en.wikipedia.org/wiki/Electrophorus-0.md
category: reference
title: Electrophorus
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrophorus
date_saved: 2026-05-05T09:42:33.988574+00:00
instance: kb-cron
parent: electrophorus-20260505-0
summary:
In electromagnetism, an electrophorus or electrophore is a simple, manual, capacitive, electrostatic generator used to produce charge via the process of electrostatic induction. A first version of it was invented in 1762 by Swedish professor Johan Carl Wilcke. Italian scientist Alessandro Volta improved and popularized the device in 1775, and is sometimes erroneously credited with its invention. The word electrophorus was coined by Volta from the Greek ήλεκτρον, elektron, and φορεύς, phoreus, meaning 'electricity bearer'. == Description and operation == The electrophorus consists of a dielectric plate (originally a 'cake' of resinous material such as pitch or wax, but in modern versions plastic is used) and a metal plate with an insulating handle. The dielectric plate is first charged through the triboelectric effect by rubbing it with fur or cloth. For this discussion, imagine the dielectric gains negative charge by rubbing, as in the illustration below. The metal plate is then placed onto the dielectric plate. The dielectric does not transfer a significant fraction of its surface charge to the metal because the microscopic contact is poor. Instead the electrostatic field of the charged dielectric causes the charges in the metal plate to separate. It develops two regions of charge


id: electroscope-20260505-0
file: data/en.wikipedia.org/wiki/Electroscope-0.md
category: reference
title: Electroscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electroscope
date_saved: 2026-05-05T09:42:35.181897+00:00
instance: kb-cron
parent: electroscope-20260505-0
summary:
The electroscope is an early scientific instrument used to detect the presence of electric charge on a body. It detects this by the movement of a test charge due to the Coulomb electrostatic force on it. The amount of charge on an object is proportional to its voltage. The accumulation of enough charge to detect with an electroscope requires hundreds or thousands of volts, so electroscopes are used with high voltage sources such as static electricity and electrostatic machines. An electroscope can only give a rough indication of the quantity of charge; an instrument that measures electric charge quantitatively is called an electrometer. The electroscope was the first electrical measuring instrument. The first electroscope was a pivoted needle (called the versorium), invented by British physician William Gilbert around 1600. The pith-ball electroscope and the gold-leaf electroscope are two classical types of electroscope that are still used in physics education to demonstrate the principles of electrostatics. A type of electroscope is also used in the quartz fiber radiation dosimeter. Electroscopes were used by the Austrian scientist Victor Hess in the discovery of cosmic rays. == Pith-ball electroscope == In 1731, Stephen Gray used a simple hanging thread, which would be attracted


id: electroscope-20260505-1
file: data/en.wikipedia.org/wiki/Electroscope-1.md
category: reference
title: Electroscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electroscope
date_saved: 2026-05-05T09:42:35.181897+00:00
instance: kb-cron
parent: electroscope-20260505-0
summary:
The gold-leaf electroscope was developed in 1787 by British clergyman and physicist Abraham Bennet, as a more sensitive instrument than pith ball or straw blade electroscopes then in use. It consists of a vertical metal rod, usually brass, from the end of which hang two parallel strips of thin flexible gold leaf. A disk or ball terminal is attached to the top of the rod, where the charge to be tested is applied. To protect the gold leaves from drafts of air they are enclosed in a glass bottle, usually open at the bottom and mounted over a conductive base. Often there are grounded metal plates or foil strips in the bottle flanking the gold leaves on either side. These are a safety measure; if an excessive charge is applied to the delicate gold leaves, they will touch the grounding plates and discharge before tearing. They also capture charge leaking through the air that accumulates on the glass walls, increasing the sensitivity of the instrument. In the precision instruments the inside of the bottle was occasionally evacuated, to prevent the charge on the terminal from leaking off through the ionization of the air. When the metal terminal is touched with


id: galvanometer-20260505-0
file: data/en.wikipedia.org/wiki/Galvanometer-0.md
category: reference
title: Galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galvanometer
date_saved: 2026-05-05T09:42:36.412179+00:00
instance: kb-cron
parent: galvanometer-20260505-0
summary:
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely. Galvanometers work by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. The mechanism is also used as an actuator in applications such as hard disks. Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current. They were the first instruments used to detect and measure small amounts of current. André-Marie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. Galvanometers have been essential for the development of science and technology in many fields. For example, in the 1800s they enabled long-range communication through submarine cables, such as the earliest transatlantic telegraph cables, and were essential to discovering the electrical activity of the heart and brain, by their fine measurements of current. Galvanometers


id: galvanometer-20260505-1
file: data/en.wikipedia.org/wiki/Galvanometer-1.md
category: reference
title: Galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galvanometer
date_saved: 2026-05-05T09:42:36.412179+00:00
instance: kb-cron
parent: galvanometer-20260505-0
summary:
=== Modern uses === Most modern uses for the galvanometer mechanism are in positioning and control systems. Galvanometer mechanisms are divided into moving magnet and moving coil galvanometers; in addition, they are divided into closed-loop and open-loop - or resonant - types. Mirror galvanometer systems are used as beam positioning or beam steering elements in laser scanning systems. For example, for material processing with high-power lasers, closed loop mirror galvanometer mechanisms are used with servo control systems. These are typically high power galvanometers and the newest galvanometers designed for beam steering applications can have frequency responses over 10 kHz with appropriate servo technology. Closed-loop mirror galvanometers are also used in similar ways in stereolithography, laser sintering, laser engraving, laser beam welding, laser TVs, laser displays and in imaging applications such as retinal scanning with Optical Coherence Tomography (OCT) and Scanning Laser Ophthalmoscopy (SLO). Almost all of these galvanometers are of the moving magnet type. The closed loop is obtained measuring the position of the rotating axis with an infrared emitter and 2 photodiodes. This feedback is an analog signal. Open loop, or resonant mirror galvanometers, are mainly used in some types of laser-based bar-code scanners, printing machines, imaging applications, military


id: galvanometer-20260505-2
file: data/en.wikipedia.org/wiki/Galvanometer-2.md
category: reference
title: Galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galvanometer
date_saved: 2026-05-05T09:42:36.412179+00:00
instance: kb-cron
parent: galvanometer-20260505-0
summary:
Edward Weston extensively improved the design of the galvanometer. He substituted the fine wire suspension with a pivot and provided restoring torque and electrical connections through spiral springs rather than through the traditional wristwatch balance wheel hairspring. He developed a method of stabilizing the magnetic field of the permanent magnet, so the instrument would have consistent accuracy over time. He replaced the light beam and mirror with a knife-edge pointer that could be read directly. A mirror under the pointer, in the same plane as the scale, eliminated parallax observation error. To maintain the field strength, Weston's design used a very narrow circumferential slot through which the coil moved, with a minimal air-gap. This improved linearity of pointer deflection with respect to coil current. Finally, the coil was wound on a lightweight form made of conductive metal, which acted as a damper. By 1888, Edward Weston had patented and brought out a commercial form of this instrument, which became a standard electrical equipment component. It was known as a "portable" instrument because it was affected very little by mounting position or by transporting it from place to place. This design is almost universally used in moving-coil meters today. Initially, laboratory


id: galvanometer-20260505-3
file: data/en.wikipedia.org/wiki/Galvanometer-3.md
category: reference
title: Galvanometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galvanometer
date_saved: 2026-05-05T09:42:36.412179+00:00
instance: kb-cron
parent: galvanometer-20260505-0
summary:
==== Geomagnetic field measurement ==== A tangent galvanometer can also be used to measure the magnitude of the horizontal component of the geomagnetic field. When used in this way, a low-voltage power source, such as a battery, is connected in series with a rheostat, the galvanometer, and an ammeter. The galvanometer is first aligned so that the coil is parallel to the geomagnetic field, whose direction is indicated by the compass when there is no current through the coils. The battery is then connected and the rheostat is adjusted until the compass needle deflects 45 degrees from the geomagnetic field, indicating that the magnitude of the magnetic field at the center of the coil is the same as that of the horizontal component of the geomagnetic field. This field strength can be calculated from the current as measured by the ammeter, the number of turns of the coil, and the radius of the coils. === Astatic galvanometer === Unlike the tangent galvanometer, the astatic galvanometer does not use the Earth's magnetic field for measurement, so it does not need to be oriented with respect to the Earth's field, making it easier to use. Developed by Leopoldo Nobili in 1825, it


id: leyden-jar-20260505-0
file: data/en.wikipedia.org/wiki/Leyden_jar-0.md
category: reference
title: Leyden jar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leyden_jar
date_saved: 2026-05-05T09:42:37.652328+00:00
instance: kb-cron
parent: leyden-jar-20260505-0
summary:
A Leyden jar (or Leiden jar, or archaically, Kleistian jar) is an electrical component that stores a high-voltage electric charge (from an external source) between electrical conductors on the inside and outside of a glass jar. It typically comprises a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil. It was the original form of the capacitor (also called a condenser). Its invention was a discovery made independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden (Leyden), Netherlands, in 1745–1746. The Leyden jar was used to conduct many early experiments in electricity, and its discovery was of fundamental importance in the study of electrostatics. It was the first means of accumulating and preserving electric charge in large quantities that could be discharged at the experimenter's will, thus overcoming a significant limit to early research into electrical conduction. Leyden jars are still used in education to demonstrate the principles of electrostatics. == Previous work == The Ancient Greeks already knew that pieces of amber could attract lightweight particles


id: leyden-jar-20260505-1
file: data/en.wikipedia.org/wiki/Leyden_jar-1.md
category: reference
title: Leyden jar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leyden_jar
date_saved: 2026-05-05T09:42:37.652328+00:00
instance: kb-cron
parent: leyden-jar-20260505-0
summary:
=== Musschenbroek and Cunaeus === The Leyden jar's invention was long credited to Pieter van Musschenbroek, the physics professor at Leiden University, who also ran a family foundry which cast brass cannonettes, and a small business (De Oosterse Lamp – "The Eastern Lamp") which made scientific and medical instruments for the new university courses in physics and for scientific gentlemen keen to establish their own 'cabinets' of curiosities and instruments. Like von Kleist, Musschenbroek was also interested in, and attempting to repeat, Bose's experiment. During this time, Andreas Cunaeus, a lawyer, learned about this experiment from Musschenbroek, and attempted to duplicate the experiment at home with household items. Unaware of the "Rule of Dufay", that the experimental apparatus should be insulated, Cunaeus held his jar in his hand while charging it, and was thus the first to discover that such an experimental setup could deliver a severe shock. He reported his procedure and experience to Swiss-Dutch natural philosopher Jean-Nicolas-Sebastian Allamand, Musschenbroek's colleague. Allamand and Musschenbroek also received severe shocks. Musschenbroek communicated the experiment in a letter from 20 January 1746 to French entomologist René Antoine Ferchault de Réaumur, who was Musschenbroek's appointed correspondent at the Paris Academy. Abbé Jean-Antoine Nollet


id: leyden-jar-20260505-2
file: data/en.wikipedia.org/wiki/Leyden_jar-2.md
category: reference
title: Leyden jar
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leyden_jar
date_saved: 2026-05-05T09:42:37.652328+00:00
instance: kb-cron
parent: leyden-jar-20260505-0
summary:
A typical design consists of a glass jar with conducting tin foil coating the inner and outer surfaces. The foil coatings stop short of the mouth of the jar, to prevent the charge from arcing between the foils. A metal rod electrode projects through the nonconductive stopper at the mouth of the jar, electrically connected by some means (usually a hanging chain) to the inner foil, to allow it to be charged. The jar is charged by an electrostatic generator, or other source of electric charge, connected to the inner electrode while the outer foil is grounded. The inner and outer surfaces of the jar store equal but opposite charges. The original form of the device is just a glass bottle partially filled with water, with a metal wire passing through a cork closing it. The role of the outer plate is provided by the hand of the experimenter. Soon John Bevis found (in 1747) that it was possible to coat the exterior of the jar with metal foil, and he also found that he could achieve the same effect by using a plate of glass with metal foil on both sides. These developments inspired William Watson in the same


id: null-detector-20260505-0
file: data/en.wikipedia.org/wiki/Null_detector-0.md
category: reference
title: Null detector
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Null_detector
date_saved: 2026-05-05T09:42:38.873146+00:00
instance: kb-cron
parent: null-detector-20260505-0
summary:
A null detectors is an electrical measurement instrument used to measure minute voltages. High precision null detectors can resolve voltage differences in the nanovolt range. Null detectors are typically designed to have high input impedance to minimize loading the circuit under test. Null detectors have historically used in calibration laboratories in conjunction with Kelvin–Varley dividers and bridge measurement circuits. Because of their sensitivity and specialized operating range, null detectors were more commonly used in laboratory than in routine field measurements. They were used as part of measurement chains that established traceability to national electrical standards, such as those maintained by National Institute of Standards and Technology (NIST). == History of Null Detectors == The development of null detectors is closely tied to the use of balance and comparison methods in electrical measurement, where the detector serves only to indicate the presence of an imbalance rather than to measure an absolute quantity. === Key stages === Galvanometers as null detectors: Early galvanometers, were commonly used as indicators of current or imbalance in circuits. In early balance and comparison arrangements, they were used to detect when two points reached equal potential, without providing calibrated measurements. Bridge circuits: The adoption of bridge circuits,


id: versorium-20260505-0
file: data/en.wikipedia.org/wiki/Versorium-0.md
category: reference
title: Versorium
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Versorium
date_saved: 2026-05-05T09:42:40.058809+00:00
instance: kb-cron
parent: versorium-20260505-0
summary:
The versorium (Latin word for "turn around") was the first electroscope, the first instrument that could detect the presence of static electric charge. It was invented in 1600 by William Gilbert, physician to Queen Elizabeth I. == Description == The versorium is a needle constructed out of metal which is allowed to pivot freely on a pedestal. It is similar to a compass needle, but unmagnetized. The needle is attracted to charged bodies brought near it, turning towards the charged object. Since it is able to distinguish between charged and non-charged objects, it is an example of a class of devices known as electroscopes. The versorium is of a similar construction to the magnetic compass, but is influenced by electrostatic rather than magnetic forces. At the time it was invented, the differences between magnetic and electrical forces were poorly understood and Gilbert did a series of experiments to prove they were two separate types of forces with the versorium and another device called a Terrella (or "little Earth"). In fact, Gilbert was the first to draw a clear distinction between magnetism and static electricity and is credited with establishing the term electricity. == How it works == The needle turns


id: wimshurst-machine-20260505-0
file: data/en.wikipedia.org/wiki/Wimshurst_machine-0.md
category: reference
title: Wimshurst machine
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Wimshurst_machine
date_saved: 2026-05-05T09:42:41.290766+00:00
instance: kb-cron
parent: wimshurst-machine-20260505-0
summary:
The Wimshurst machine or Wimshurst influence machine is an electrostatic generator capable of generating high voltages. It was developed between 1880 and 1883 by British inventor James Wimshurst (1832–1903). It has a distinctive appearance with two large contra-rotating discs mounted in a vertical plane, two crossed bars with metallic brushes, and a spark gap formed by two metal spheres. == Design == These machines belong to a class of electrostatic generators called influence machines, which separate electric charges through electrostatic induction, or influence, not depending on friction for their operation. Earlier machines in this class were developed by Wilhelm Holtz (1865 and 1867), August Toepler (1865), J. Robert Voss (1880), and others. The older machines are less efficient and exhibit an unpredictable tendency to switch their polarity, while the Wimshurst machine has neither defect. In a Wimshurst machine, the two insulated discs and their metal sectors rotate in opposite directions passing the crossed metal neutralizer bars and their brushes. An imbalance of charges is induced, amplified, and collected by two pairs of brushes or metal combs with points placed near the surfaces of each disc. These collectors are mounted on insulating supports and connected to the output terminals. The positive


id: optical-instrument-20260505-0
file: data/en.wikipedia.org/wiki/Optical_instrument-0.md
category: reference
title: Optical instrument
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Optical_instrument
date_saved: 2026-05-05T09:42:42.800539+00:00
instance: kb-cron
parent: optical-instrument-20260505-0
summary:
An optical instrument is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common examples include periscopes, microscopes, telescopes, and cameras. == Image enhancement == The first optical instruments were telescopes used for magnification of distant images, and microscopes used for magnifying very tiny images. Since the days of Galileo and Van Leeuwenhoek, these instruments have been greatly improved and extended into other portions of the electromagnetic spectrum. The binocular device is a generally compact instrument for both eyes designed for mobile use. A camera could be considered a type of optical instrument, with the pinhole camera and camera obscura being very simple examples of such devices. == Analysis == Another class of optical instrument is used to analyze the properties of light or optical materials. They include: Interferometer for measuring the interference properties of light waves Photometer for measuring light intensity Polarimeter for measuring dispersion or rotation of polarized light Reflectometer for measuring the reflectivity of a surface or object Refractometer for measuring refractive index of various materials Spectrometer or monochromator for generating or measuring a portion of the optical spectrum, for the purpose of


id: autocollimator-20260505-0
file: data/en.wikipedia.org/wiki/Autocollimator-0.md
category: reference
title: Autocollimator
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Autocollimator
date_saved: 2026-05-05T09:42:43.937135+00:00
instance: kb-cron
parent: autocollimator-20260505-0
summary:
An autocollimator is an optical instrument for non-contact measurement of angles. They are typically used to align components and measure deflections in optical or mechanical systems. An autocollimator works by projecting an image onto a target mirror and measuring the deflection of the returned image against a scale, either visually or by means of an electronic detector. A visual autocollimator can measure angles as small as 1 arcsecond (4.85 microradians), while an electronic autocollimator can have up to 100 times more resolution. Visual autocollimators are often used for aligning laser rod ends and checking the face parallelism of optical windows and wedges. Electronic and digital autocollimators are used as angle measurement standards, for monitoring angular movement over long periods of time and for checking angular position repeatability in mechanical systems. Servo autocollimators are specialized compact forms of electronic autocollimators that are used in high-speed servo-feedback loops for stable-platform applications. An electronic autocollimator is typically calibrated to read the actual mirror angle. == Electronic autocollimator == The electronic autocollimator is a high precision angle measurement instrument capable of measuring angular deviations with accuracy down to fractions of an arcsecond, by electronic means only, with no optical eye-piece. Electronic autocollimator measurement offers


id: cast-glance-20260505-0
file: data/en.wikipedia.org/wiki/Cast_Glance-0.md
category: reference
title: Cast Glance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cast_Glance
date_saved: 2026-05-05T09:42:45.118201+00:00
instance: kb-cron
parent: cast-glance-20260505-0
summary:
Cast Glance is a gyrostabilized optical instrument used by the United States Navy and United States Air Force. It is an airborne system that is used by Air Test and Evaluation Squadron 30 (VX-30) on board the Lockheed NP-3D variant of the P-3 Orion. The system consists of a moving gyro-stabilised mirror with fixed optics, two fixed cameras and five sensors. The cameras look out of the starboard side of the aircraft. The system is photometric and enables the simultaneous recording of the electro-optical to the infrared spectrum and medium wave IR. The system provides photographic coverage of air-to-air, air-to-surface or surface-to-air test operations. Cast Glance was also used to support the Space Shuttle program. == References == == External links == Cast Glance Near Infrared Imaging - Futron Corporation Video imagery produced by Cast Glance (from 02:57)


id: cathetometer-20260505-0
file: data/en.wikipedia.org/wiki/Cathetometer-0.md
category: reference
title: Cathetometer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathetometer
date_saved: 2026-05-05T09:42:46.323492+00:00
instance: kb-cron
parent: cathetometer-20260505-0
summary:
A cathetometer is an instrument for measuring vertical distances in cases where a scale cannot be placed very close to the points whose distance apart is desired. The instrument consists essentially of an accurately graduated scale and a horizontal telescope capable of being moved up and down a rigid vertical column. The position of the telescope can be read by means of an attached Vernier scale. In measuring the vertical distance between two points, the instrument must first be leveled. Next, the cross hair in the eyepiece of the horizontal telescope is brought into coincidence with the image of one point and the position of the telescope noted; the cross hair is then brought into coincidence with the image of the other point and the new position of the telescope noted. The difference between these readings is the vertical distance required. Among the uses of a cathetometer is reading the levels of a liquid in a capillary tube, such as in measurements of surface tension. A cathetometer also can be used for following the changes in liquid level in a dilatometer due to, for example, a chemical reaction therein. == See also == Travelling microscope == References ==


