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Tusi Couple
The Tusi couple (also known as Tusi's mechanism) is a mathematical device in which a small circle rotates inside a larger circle twice the diameter of the smaller circle. Rotations of the circles cause a point on the circumference of the smaller circle to Oscillation (mathematics), oscillate back and forth in linear motion along a diameter of the larger circle. The Tusi couple is a two-cusped hypocycloid. The couple was first proposed by the 13th-century Persian people, Persian Islamic astronomy, astronomer and Islamic mathematics, mathematician Nasir al-Din al-Tusi in his 1247 ''Tahrir al-Majisti'' (''Commentary on the Almagest'') as a solution for the latitudinal motion of the inferior planets and later used extensively as a substitute for the equant introduced over a thousand years earlier in Ptolemy's ''Almagest''. Original description The translation of the copy of Tusi's original description of his geometrical model alludes to at least one inversion of the model to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roulette (curve)
In the differential geometry of curves, a roulette is a kind of curve, generalizing cycloids, epicycloids, hypocycloids, trochoids, epitrochoids, hypotrochoids, and involutes. On a basic level, it is the path traced by a curve while rolling on another curve without slipping. Definition Informal definition Roughly speaking, a roulette is the curve described by a point (called the ''generator'' or ''pole'') attached to a given curve as that curve rolls without slipping, along a second given curve that is fixed. More precisely, given a curve attached to a plane which is moving so that the curve rolls, without slipping, along a given curve attached to a fixed plane occupying the same space, then a point attached to the moving plane describes a curve, in the fixed plane called a roulette. Special cases and related concepts In the case where the rolling curve is a line and the generator is a point on the line, the roulette is called an involute of the fixed curve. If the rol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proclus
Proclus Lycius (; 8 February 412 – 17 April 485), called Proclus the Successor (, ''Próklos ho Diádokhos''), was a Greek Neoplatonist philosopher, one of the last major classical philosophers of late antiquity. He set forth one of the most elaborate and fully developed systems of Neoplatonism and, through later interpreters and translators, exerted an influence on Byzantine philosophy, early Islamic philosophy, scholastic philosophy, and German idealism, especially G. W. F. Hegel, who called Proclus's ''Platonic Theology'' "the true turning point or transition from ancient to modern times, from ancient philosophy to Christianity." Biography The primary source for the life of Proclus is the eulogy ''Proclus'', ''or On Happiness'' that was written for him upon his death by his successor, Marinus, Marinus' biography set out to prove that Proclus reached the peak of virtue and attained eudaimonia. There are also a few details about the time in which he lived in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Library Of Congress
The Library of Congress (LOC) is a research library in Washington, D.C., serving as the library and research service for the United States Congress and the ''de facto'' national library of the United States. It also administers Copyright law of the United States, copyright law through the United States Copyright Office, and it houses the Congressional Research Service. Founded in 1800, the Library of Congress is the oldest Cultural policy of the United States, federal cultural institution in the United States. It is housed in three buildings on Capitol Hill, adjacent to the United States Capitol, along with the National Audio-Visual Conservation Center in Culpeper, Virginia, and additional storage facilities at Fort Meade, Fort George G. Meade and Cabin Branch in Hyattsville, Maryland. The library's functions are overseen by the librarian of Congress, and its buildings are maintained by the architect of the Capitol. The LOC is one of the List of largest libraries, largest libra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medieval Greek
Medieval Greek (also known as Middle Greek, Byzantine Greek, or Romaic; Greek: ) is the stage of the Greek language between the end of classical antiquity in the 5th–6th centuries and the end of the Middle Ages, conventionally dated to the Ottoman conquest of Constantinople in 1453. From the 7th century onwards, Greek was the only language of administration and government in the Byzantine Empire. This stage of language is thus described as Byzantine Greek. The study of the Medieval Greek language and literature is a branch of Byzantine studies, the study of the history and culture of the Byzantine Empire. The conquests of Alexander the Great, and the ensuing Hellenistic period, had caused Greek to spread throughout Anatolia and the Eastern Mediterranean. The beginning of Medieval Greek is occasionally dated back to as early as the 4th century, either to 330 AD, when the political centre of the Roman Empire was moved to Constantinople, or to 395 AD, the division o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gregory Chioniades
Gregory Chioniades (; c. 1240 – c. 1320) was a Byzantine Greek astronomer. He traveled to Persia, where he learned Persian mathematical and astronomical science, which he introduced into Byzantium upon his return from Persia and founded an astronomical academy at Trebizond. Choniades also served as Orthodox bishop in Tabriz. Biography Information about Chioniades survives from some contemporary sources. In 1347, George Chrysokokkes wrote that He was born in Constantinople, probably around 1240, and was originally named George. Sixteen of Chioniades' letters have survived, which confirm that he received assistance from Alexios II and traveled to Persia. Chioniades translated a number of Arabic and Persian works on mathematics and astronomy, including the astronomical tables of his teacher Shams al-Din al-Bukhari, who had worked at the famous Maragheh observatory under the polymath Nasir al-Din al-Tusi. Chioniades played an important role in transmitting several innovations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byzantine Science
Scientific scholarship during the Byzantine Empire played an important role in the transmission of classical knowledge to the Islamic world and to Renaissance Italy, and also in the transmission of Islamic science to Renaissance Italy. Its rich historiographical tradition preserved ancient knowledge upon which splendid art, architecture, literature and technological achievements were built. Byzantines stood behind several technological advancements. Classical and ecclesiastical studies Byzantine science was essentially classical science. Therefore, Byzantine science was in every period closely connected with ancient-pagan philosophy and metaphysics. Despite some opposition to pagan learning, many of the most distinguished classical scholars held high office in the Church. The writings of antiquity never ceased to be cultivated in the Byzantine Empire because of the impetus given to classical studies by the Academy of Athens in the 4th and 5th centuries B.C., the vigor of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Saliba
George Saliba (Arabic: جورج صليبا) is a Lebanese-American historian who is Professor of Arabic and Islamic Science at the Department of Middle Eastern, South Asian, and African Studies, Columbia University, New York, where he has been since 1979. Saliba is currently the founding director of the Farouk Jabre Center for Arabic & Islamic Science & Philosophy and the Jabre-Khwarizmi Chair in the History Department. Early life and education Saliba received a bachelors and master's degree in mathematics from the American University of Beirut. After, he received a master of science degree in Semitic languages and a doctorate in Islamic sciences from the University of California, Berkeley. Career Saliba has been at Columbia University since 1979. He studies the development of scientific ideas from late antiquity till early modern times, with a special focus on the various planetary theories that were developed within the Islamic civilization and the impact of such theories on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guillaume Postel
Guillaume Postel (25 March 1510 – 6 September 1581) was a French linguist, Orientalist, astronomer, Christian Kabbalist, diplomat, polyglot, professor, religious universalist, and writer. Born in the village of Barenton in Normandy, Postel made his way to Paris to further his education. While studying at the Collège Sainte-Barbe, he became acquainted with Ignatius of Loyola and many of the men who would become the founders of the Society of Jesus, retaining a lifelong affiliation with them. He entered Rome in the novitiate of the Jesuits in March 1544, but left on December 9, 1545 before making religious vows. Diplomacy and scholarship Postel was adept at Arabic, Hebrew, and Syriac and other Semitic languages, as well as the Classical languages of Ancient Greek and Latin, and soon came to the attention of the French court. Travel to the Ottoman Empire In 1536, when Francis I sought a Franco-Ottoman alliance with the Ottoman Turks, he sent Postel as the official int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trepidation
Trepidation (from Lat. ''trepidus'', "trepidatious"), in now-obsolete medieval theories of astronomy, refers to hypothetical oscillation in the precession of the equinoxes. The theory was popular from the 9th to the 16th centuries. The origin of the theory of trepidation comes from the ''Small Commentary to the Handy Tables'' written by Theon of Alexandria in the 4th century CE. In precession, the equinoxes appear to move slowly through the ecliptic, completing a revolution in approximately 25,800 years (according to modern astronomers). Theon states that certain (unnamed) ancient astrologers believed that the precession, rather than being a steady unending motion, instead reverses direction every 640 years. The equinoxes, in this theory, move through the ecliptic at the rate of 1 degree in 80 years over a span of 8 degrees, after which they suddenly reverse direction and travel back over the same 8 degrees. Theon describes but does not endorse this theory. A more sophisticated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (planet)
Mercury is the first planet from the Sun. It is a rocky planet with a trace atmosphere. While it is the List of Solar System objects by size, smallest and least massive planet of the Solar System, its surface gravity is slightly higher than that of Mars. The surface of Mercury is similar to Earth's Moon, heavily Impact crater, cratered, with expansive rupes system, generated from thrust faults, and bright ray systems, formed by ejecta. Its largest crater, Caloris Planitia, has a diameter of , which is about one-third the diameter of the planet (). Being the most inferior planet, inferior orbiting planet it appears in Earth's sky, always close to the Sun, either as a "morning star" or an "evening star". It stays most of the time the closest to all other planets and is the planet with the highest delta-v needed to travel to from all other planets of the Solar System. Mercury's sidereal year (88.0 Earth days) and sidereal day (58.65 Earth days) are in a 3:2 ratio. This relation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
De Revolutionibus Orbium Coelestium
''De revolutionibus orbium coelestium'' (English translation: ''On the Revolutions of the Heavenly Spheres'') is the seminal work on the heliocentric theory of the astronomer Nicolaus Copernicus (1473–1543) of the Polish Renaissance. The book, first printed in 1543 in Nuremberg, Holy Roman Empire, offered an alternative model of the universe to Ptolemy's geocentric system, which had been widely accepted since ancient times. History Copernicus initially outlined his system in a short, untitled, anonymous manuscript that he distributed to several friends, referred to as the '' Commentariolus''. A physician's library list dating to 1514 includes a manuscript whose description matches the ''Commentariolus'', so Copernicus must have begun work on his new system by that time. Most historians believe that he wrote the ''Commentariolus'' after his return from Italy, possibly only after 1510. At this time, Copernicus anticipated that he could reconcile the motion of the Earth with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
