Burgi, Jost

SUBJECT AREA: Horology
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b. 28 February 1552 Lichtensteig, Switzerland
d. 31 January 1632 Kassel, Germany
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Swiss clockmaker and mathematician who invented the remontoire and the cross-beat escapement, also responsible for the use of exponential notation and the calculation of tables of anti-logarithms.
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Burgi entered the service of Duke William IV of Hesse in 1579 as Court Clockmaker, although he also assisted William with his astronomical observations. In 1584 he invented the cross-beat escapement which increased the accuracy of spring-driven clocks by two orders of magnitude. During the last years of the century he also worked on the development of geometrical and astronomical instruments for the Royal Observatory at Kassel.
On the death of Duke Wilhelm in 1603, and with news of his skills having reached the Holy Roman Emperor Rudolph II, in 1604 he went to Prague to become Imperial Watchmaker and to assist in the creation of a centre of scientific activity, subsequently becoming Assistant to the German astronomer, Johannes Kepler. No doubt this association led to an interest in mathematics and he made significant contributions to the concept of decimal fractions and the use of exponential notation, i.e. the use of a raised number to indicate powers of another number. It is likely that he was developing the idea of logarithms at the same time (or possibly even before) Napier, for in 1620 he made his greatest contribution to mathematics, science and, eventually, engineering, namely the publication of tables of anti-logarithms.
At Prague he continued the series of accurate clocks and instruments for astronomical measurements that he had begun to produce at Kassel. At that period clocks were very poor timekeepers since the controller, the foliot or balance, had no natural period of oscillation and was consequently dependent on the driving force. Although the force of the driving weight was constant, irregularities occurred during the transmission of the power through the train as a result of the poor shape and quality of the gearing. Burgi attempted to overcome this directly by superb craftsmanship and indirectly by using a remontoire. This device was wound at regular intervals by the main driving force and fed the power directly to the escape wheel, which impulsed the foliot. He also introduced the crossbeat escapement (a variation on the verge), which consisted of two coupled foliots that swung in opposition to each other. According to contemporary evidence his clocks produced a remarkable improvement in timekeeping, being accurate to within a minute a day. This improvement was probably a result of the use of a remontoire and the high quality of the workmanship rather than a result of the cross-beat escapement, which did not have a natural period of oscillation.
Burgi or Prague clocks, as they were known, were produced by very few other makers and were supplanted shortly afterwards by the intro-duction of the pendulum clock. Burgi also produced superb clockwork-driven celestial globes.
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Principal Honours and Distinctions
Ennobled 1611.
Bibliography
Burgi only published one book, and that was concerned with mathematics.
Further Reading
L.von Mackensen, 1979, Die erste Sternwarte Europas mit ihren Instrumenten and Uhren—400 Jahre Jost Burgi in Kassel, Munich.
K.Maurice and O.Mayr (eds), 1980, The Clockwork Universe, Washington, DC, pp. 87– 102.
H.A.Lloyd, 1958, Some Outstanding Clocks Over 700 Years, 1250–1950, London. E.T.Bell, 1937, Men of Mathematics, London: Victor Gollancz.
See also: Briggs, Henry
KF / DV

Biographical history of technology. - Taylor & Francis e-Librar. . 2005.

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