Torquetum

A torquetum or Turquetum (Latin torquetum, turquetum, turketum and other word variations as masculine with -us, Eng. Turquet and French ) is an astronomical instrument that combines the functions of an armillary sphere and an astrolabe and allows the coordinates a celestial body and its current altitude and time by unequal hours to be determined.

Bulk

The origin of the name is uncertain. It is usually ' turn, twist " from the Latin torqueri derived, but was apparently already in the Middle Ages brought with turcus " Turkish " in conjunction. The origin of the instrument is unknown. It may be an Arab invention and is often specially issued as an invention of Gabir ibn Aflah (encoder ), the two instruments described in the first half of the 12th century, but which may possibly apply as a precursor.

The oldest descriptions can be found in two Latin texts. This is on the one hand by a traditional in numerous manuscripts Tractatus de torqueto whose transcript or oldest dated copy was completed on July 2, 1284 in Paris. The mentioned in the manuscripts writer, Franco de Polonia is not otherwise known, occasionally contemplated his identity with the at that time also teaches in Paris German music theorist Franco of Cologne ( " Franco de Colonia " ) is not secured. A further description of Torquetums found in the Tractatus super totam astrologiam of also not issues highlighted by other writings Franciscan friar and professor Bernard of Verdun ( Bernardus de Virduno ), the font is not safe to date, but in any case not before 1264 and probably not after 1320 arose.

Further evidence of knowledge and use of the instrument resulting from comet observations from 1299 with Peter of Limoges ( Peter Lemovicensis ) and 1301 (anonymous, possibly also of Peter of Limoges ). Johannes de Muris also used the instrument for a measurement on 12 March 1318. Extensive tracts were later of John of Gmunden ( † 1442 ), or one of his pupils and by Johannes Regiomontanus Johannes and Peter Apian ( 1532) written.

The oldest pictures are found in a dating from the mid-14th century manuscript of the Ashmolean Library in Oxford. The oldest surviving instruments date from the possession of Martin Bylica (produced by Hans Dorn) and of Nicholas of Cusa. The latter had purchased the instrument in Nuremberg. According to publish in the Journal of Instrument tuition in December 1920 examinations Hartmanns the Turks device of Cusa was built around the year 1434.

One also art historical significance representation of the instrument can be found on the painting " The French ambassador " by Hans Holbein the Younger.