Gaspard de Prony
Gaspard Clair François Marie Riche de Prony (July 22, 1755 - July 29, 1839) was a French mathematician and engineer, who worked on hydraulics. He was born at Chamelet, Beaujolais, France and died in Asnières-sur-Seine, France.
Education and early works
He was Engineer-in-Chief of the École Nationale des Ponts et Chaussées.
The trigonometric and logarithmic tables of the cadastre
In 1793, de Prony began a major task of producing logarithmic and trigonometric tables for the French Cadastre. The effort was begun at the request of the French National Assembly, which, after the French Revolution wanted to bring uniformity to the multiple measurements and standards used throughout the nation. The tables and their production were vast, with values calculated to between fourteen and twenty-nine decimal places. Inspired by Adam Smith's Wealth of Nations, de Prony divided up the labor, bragging that he "could manufacture logarithms as easily as one manufactures pins." At the top of the organizational hierarchy were scientists and mathematicians who devised the formulas. Next were workers who created the instructions for doing the calculations. At the bottom were about ninety "computers" (as they were called) who were not trained in mathematics, but who followed the instructions."
Getting such a massive work published proved to be difficult and in fact the tables were never published in full, as a consequence of the loss of value of paper money during the French Revolution. Only in 1891 was an excerpt of the table published.
One of de Prony's important scientific inventions was the 'de Prony brake' which he invented in 1821 to measure the performance of machines and engines. He also was first to propose using a reversible pendulum to measure gravity, which was independently invented in 1817 by Henry Kater and became known as the Kater's pendulum.
Prony's estimation method
He also created a method of converting sinusoidal and exponential curves into a systems of linear equations. Prony estimation is used extensively in signal processing and finite element modelling of non linear materials.
Prony was a member, and eventually president, of the French Academy of Science. He was also elected a foreign member of the Royal Swedish Academy of Sciences in 1810. His name is one of the 72 names inscribed on the Eiffel Tower.
- Bradley, Margaret. A career biography of Gaspard Clair Francois Marie Riche De Prony, bridge-builder, educator, and scientist. Mellen Press. 1998.
- In 1793, Prony was asked by Lazare Carnot to build very accurate tables.
- However, one must distinguish the number of places of calculation from the number of places of accuracy. These tables were not accurate to 14 and 29 places.
- Grier, David Alan. When Computers Were Human. Princeton University Press. 2005. pp. 36.
- Grier, David Alan. When Computers Were Human. Princeton University Press. 2005. pp. 33-39.
- The site http://locomat.loria.fr contains a detailed analysis of Prony's tables.
- LS-DYNDA Keyword Manual. Livermore Software Technology Corporation. 2009. pp289