Jost Bürgi, or Joost, or Jobst Bürgi (February 28, 1552, Lichtensteig, Switzerland – January 31, 1632), active primarily at the courts in Kassel and Prague, was a Swiss clockmaker, a maker of astronomical instruments and a mathematician.
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Jost Bürgi is widely considered one of the most innovative and most skillful 'mechanics' of his era. It has been suggested that he should also be counted among the leading astronomers of his time because his unprecedented ability to design and construct mechanical models of the movement of heavenly bodies proves an advanced level of insight into celestial mechanics. His classification as a scholar is controversial because he lacked a formal education and did not know Latin, the only language of scholarly publications at the time. Another autodidact, Nicolaus Reimers, in 1587 translated Copernicus' De Revolutionibus Orbium Coelestium into German for Bürgi. A copy of the translation survived in Graz, it is thus called "Grazer Handschrift".[1][2][3]
He left few written records of his work. However other historians of science claim that Bürgi's legacy of many unique and innovative mechanical astronomical models should be considered an unorthodox method of 'publishing' astronomical insights.[4] During his years in Praha he worked closely with the astronomer Johannes Kepler at the court of Rudolf II.
It is undocumented where he learned his clockmaking skills, but eventually he became the most innovative clock and scientific instrument maker of his time.[5][6] Among his major horological inventions were the cross-beat escapement, and the remontoire, two mechanisms which improved the accuracy of mechanical clocks of the time by orders of magnitude.[7] This allowed for the first time clocks to be used as scientific instruments, with enough accuracy to time the passing of stars (and other heavenly bodies) in the crosshairs of telescopes to start accurately charting stellar positions.
Working as an instrument maker for the court of William IV, Landgrave of Hesse-Kassel in Kassel[8] he played a pivotal role in developing the first astronomical charts. He invented logarithms as a working tool for himself for his astronomical calculations, but as a "craftsman/scholar" rather than a "book scholar" he failed to publish his invention for a long time.[4]
In 1592 Rudolf II, Holy Roman Emperor in Prague received from his uncle, the Landgrave of Hesse-Kassel, a Bürgi globe and insisted that Bürgi deliver it personally. From then on Bürgi commuted between Kassel and Prague, and finally entered the service of the emperor in 1604 to work for the imperial astronomer Johannes Kepler.[9]
The most significant artifacts designed and built by Burgi surviving in museums are:
He invented logarithms independently of John Napier, since his method is distinct from Napier's. Napier published his discovery in 1614, and this publication was widely disseminated in Europe by the time Bürgi published at the behest of Johannes Kepler. There is evidence[10] that Bürgi arrived at his invention as early as 1588, six years before Napier began work on the same idea. By delaying the publication of his work to 1620, Bürgi lost his claim for priority in historic discovery.[11] Bürgi was also a major contributor to prosthaphaeresis, a technique for computing products quickly using trigonometric identities, which predated logarithms.
The lunar crater Byrgius is named in his honor.
Bürgi's Progress Tabulen (1620): logarithmic tables without logarithms * http://www.loria.fr/~roegel/locomat.html