Theodosius of Bithynia

Theodosius of Bithynia (Greek Θεοδόσιος; * second half of the 2nd century and 1st century BC) was a Greek mathematician and astronomer. He is quoted as Theodosius of Tripoli.

About Theodosius little is known. Strabo calls him one of the most important scholars of Bithynia, and also his sons were known by Strabo mathematician. Since Strabo mentions him in his geography in his list after Hipparchus and he proceeds usually chronologically, Theodosius is likely to be temporary then classified according to Hipparchus.

In the Byzantine encyclopedia Suda is specified as the origin Tripoli, but is probably a mistake before. The entry in the Suda but has often meant that he is also known as Theodosius of Tripoli.

From Theodosius three works have been preserved:

• Gauge ball ( sphaerica ), in three volumes. It covers the basic geometry of the sphere, which was needed for astronomical purposes and was often seen by the Greeks as a part of astronomy. It is based on Autolycus of Pitane and Euclid, and from the latter not on the elements ( the little ball to geometry included) but its known only in fragments astronomical phenomena work. But he does not consider the development of the sphere of teaching by his compatriot Hipparchus of Bithynia. The work was probably like the other surviving works of Theodosius part of a collection to the Little Astronomy of Pappus and is therefore preserved. It was the end of the 9th century (as well as the other works of Theodosius ) into Arabic ( Thabit ibn Qurra among others ) and from there in the 12th century translated into Latin (Plato of Tivoli, Gerard of Cremona ). Printed editions First published in 1518 in Venice (in Latin, translation from Arabic ), in 1529 in Vienna (John Vögelin ), in 1558 in Paris (J. Pena ), 1572 in Strasbourg ( Conrad Dasypodius ) and then among other things, by Clavius ​​(Rome 1586), J. Auria (Rome 1587 ), Marin Mersenne ( 1644), Isaac Barrow ( 1675).
• About residences and over days and nights, both for mathematical geography. In the first work is described, inter alia, that the sky parts are visible at different geographical locations and in the second work is about the length of days and nights during the year.

He is said to have written even after the Suda some other minor astronomical and astrological works, a book description of houses (which probably does not mean astrology but architecture) and a comment on the method of Archimedes.

He is probably identical with the above-mentioned by Vitruvius as the inventor of a deployable at different sundial Örtern Theodosius.

Writings

• Theodosius Tripolites sphaerica, issue of J. Heiberg in Proceedings of the Society of Sciences at Gottingen, Phil. - Hist. Class, Volume 19, No.3, 1927 (in Greek with Latin translation and Scholium ) German editions: Johann Ernst Nizze The Spheres of Theodosius Stralsund in 1826; Arthur Czwalina Autolycus: Rotating ball and the rising and setting of the stars; Theodosius of Tripoli: Spheres, Ostwald's classic, Akademische Verlagsgesellschaft, Leipzig 1931
• French edition: Paul ver Eecke Théodose de Tripoli: Les sphériques, Paris, Bruges 1927