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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| History of cartography | 9/16 | https://en.wikipedia.org/wiki/History_of_cartography | reference | science, encyclopedia | 2026-05-05T03:59:26.449661+00:00 | kb-cron |
===== Book on the appearance of the Earth ===== Muhammad ibn Mūsā al-Khwārizmī's Kitāb ṣūrat al-Arḍ ("Book on the appearance of the Earth") was completed in 833. It is a revised and completed version of Ptolemy's Geography, consisting of a list of 2402 coordinates of cities and other geographical features following a general introduction. Al-Khwārizmī, Al-Ma'mun's most famous geographer, corrected Ptolemy's gross overestimate for the length of the Mediterranean Sea (from the Canary Islands to the eastern shores of the Mediterranean); Ptolemy overestimated it at 63 degrees of longitude, while al-Khwarizmi almost correctly estimated it at nearly 50 degrees of longitude. Al-Ma'mun's geographers "also depicted the Atlantic and Indian Oceans as open bodies of water, not land-locked seas as Ptolemy had done." Al-Khwarizmi thus set the Prime Meridian of the Old World at the eastern shore of the Mediterranean, 10–13 degrees to the east of Alexandria (the prime meridian previously set by Ptolemy) and 70 degrees to the west of Baghdad. Most medieval Muslim geographers continued to use al-Khwarizmi's prime meridian. Other prime meridians used were set by Abū Muhammad al-Hasan al-Hamdānī and Habash al-Hasib al-Marwazi at Ujjain, a centre of Indian astronomy, and by another anonymous writer at Basra.
===== Al-Biruni ===== Abu Rayhan al-Biruni (973–1048) gave an estimate of 6,339.6 km for the Earth radius, which is only 17.15 km less than the modern value of 6,356.7523142 km (WGS84 polar radius "b"). In contrast to his predecessors who measured the Earth's circumference by sighting the Sun simultaneously from two different locations, Al-Biruni developed a new method of using trigonometric calculations based on the angle between a plain and mountain top which yielded more accurate measurements of the Earth's circumference and made it possible for it to be measured by a single person from a single location. Al-Biruni's method's motivation was to avoid "walking across hot, dusty deserts" and the idea came to him when he was on top of a tall mountain in India (present day Pind Dadan Khan, Pakistan). From the top of the mountain, he sighted the dip angle which, along with the mountain's height (which he calculated beforehand), he applied to the law of sines formula. This was the earliest known use of dip angle and the earliest practical use of the law of sines. Around 1025, Al-Biruni was the first to describe a polar equi-azimuthal equidistant projection of the celestial sphere. In his Codex Masudicus (1037), Al-Biruni theorized the existence of a landmass along the vast ocean between Asia and Europe, or what is today known as the Americas. He deduced its existence on the basis of his accurate estimations of the Earth's circumference and Afro-Eurasia's size, which he found spanned only two-fifths of the Earth's circumference, and his discovery of the concept of specific gravity, from which he deduced that the geological processes that gave rise to Eurasia must've also given rise to lands in the vast ocean between Asia and Europe. He also theorized that the landmass must be inhabited by human beings, which he deduced from his knowledge of humans inhabiting the broad north–south band stretching from Russia to South India and Sub-Saharan Africa, theorizing that the landmass would most likely lie along the same band. He was the first to predict "the existence of land to the east and west of Eurasia, which later on was discovered to be America and Japan".
===== Tabula Rogeriana =====
The Arab geographer, Muhammad al-Idrisi, produced his medieval atlas, Tabula Rogeriana or The Recreation for Him Who Wishes to Travel Through the Countries, in 1154. He incorporated the knowledge of Africa, the Indian Ocean and the Far East gathered by Arab merchants and explorers with the information inherited from the classical geographers to create the most accurate map of the world in pre-modern times. With funding from Roger II of Sicily (1097–1154), al-Idrisi drew on the knowledge collected at the university of Cordoba and paid draftsmen to make journeys and map their routes. The book describes the earth as a sphere with a circumference of 22,900 miles (36,900 km) but maps it in 70 rectangular sections. Notable features include the correct dual sources of the Nile, the coast of Ghana and mentions of Norway. Climate zones were a chief organizational principle. A second and shortened copy from 1192 called Garden of Joys is known by scholars as the Little Idrisi. On the work of al-Idrisi, S. P. Scott commented:
The compilation of Edrisi marks an era in the history of science. Not only is its historical information most interesting and valuable, but its descriptions of many parts of the earth are still authoritative. For three centuries geographers copied his maps without alteration. The relative position of the lakes which form the Nile, as delineated in his work, does not differ greatly from that established by Baker and Stanley more than seven hundred years afterwards, and their number is the same. The mechanical genius of the author was not inferior to his erudition. The celestial and terrestrial planisphere of silver which he constructed for his royal patron was nearly six feet in diameter, and weighed four hundred and fifty pounds; upon the one side the zodiac and the constellations, upon the other—divided for convenience into segments—the bodies of land and water, with the respective situations of the various countries, were engraved. Al-Idrisi's atlas, originally called the Nuzhat in Arabic, served as a major tool for Italian, Dutch and French mapmakers from the 16th century to the 18th century.
==== Piri Reis map of the Ottoman Empire ====
The Ottoman cartographer Piri Reis published navigational maps in his Kitab-ı Bahriye. The work includes an atlas of charts for small segments of the mediterranean, accompanied by sailing instructions covering the sea. In the second version of the work, he included a map of the Americas. The Piri Reis map drawn by the Ottoman cartographer Piri Reis in 1513, is one of the oldest surviving maps to show the Americas.
=== Medieval Europe ===