Guillaume Amontons

French scientific instrument inventor and physicist (1663-1705) "Amontons" redirects here. For the lunar crater, see Amontons (crater).

Guillaume Amontons

Born	31 August 1663 (1663-08-31) Paris, France
Died	11 October 1705 (1705-10-12) (aged 42) Paris, France
Nationality	French
Known for	Amontons' laws Hot air engine Thermodynamic temperature
Scientific career
Fields	Physics

Guillaume Amontons (31 August 1663 – 11 October 1705) was a French scientific instrument inventor and physicist. He was one of the pioneers in studying the problem of friction, which is the resistance to motion when bodies make contact. He is also known for his work on thermodynamics, the concept of absolute zero, and early engine design.

Life

Guillaume was born in Paris, France. His father was a lawyer from Normandy who had moved to the French capital. While still young, Guillaume lost his hearing and became mostly deaf. According to one biographer, Fontenelle, while studying perpetual motion, he became convinced of the importance of studying machines from a mathematical perspective. He never attended a university, but was able to study mathematics, the physical sciences, and celestial mechanics. He also spent time studying the skills of drawing, surveying, and architecture. He died in Paris, France.

Work

He was supported in his research career by the government, and was employed in various public works projects.

Scientific instruments

Among his contributions to scientific instrumentation were improvements to the barometer (1695), hygrometer (1687), and thermometer (1695), particularly for use of these instruments at sea. He also demonstrated an optical telegraph and proposed the use of his clepsydra (water clock) for keeping time on a ship at sea.

Thermodynamics

Amontons investigated the relationship between pressure and temperature in gases though he lacked accurate and precise thermometers. Though his results were at best semi-quantitative, he established that the pressure of a gas increases by roughly one-third between the temperatures of cold and the boiling point of water. This was a substantial step towards the subsequent gas laws and, in particular, Gay-Lussac's law. His work led him to speculate that a sufficient reduction in temperature would lead to the disappearance of pressure. Though he came close to finding absolute zero - the theoretical temperature by which the volume of air in his air-thermometer will be reduced to nothing (estimated by him as −240° on the Celsius scale), the discovery would not be complete until at least a century later.

Guillaume Amontons is also the inventor of the hot air engine. In 1699, he built his first engine, more than a century earlier than the well-known Stirling engine. This engine, named by Amontons a "fire mill" (moulin à feu) followed a new thermodynamic cycle, which later became known as the Stirling cycle.

The fire mill is a wheel that makes use of the expansion of heated air to generate motive power. The calculated power of Amontons' fire mill was 39 HP, equal to the power of the most powerful hot air engines of the 19th century (with the exception of the "caloric engine" of Ericsson). The main difference between Amontons' engine and the hot air engines of the 19th century was the nature of the piston (Amontons used water) and the use of rotational motion instead of alternating motion.

Friction

In 1699, Amontons published his rediscovery of the laws of friction first put forward by Leonardo da Vinci. Though they were received with some skepticism, the laws were verified by Charles-Augustin de Coulomb in 1781. For this contribution, Amontons was named as one of the 23 "Men of Tribology" by Duncan Dowson.

Amontons' laws of friction

Amontons-Coulomb laws of friction:

The force of friction is directly proportional to the applied load. (Amontons' 1st law)
The force of friction is independent of the apparent area of contact. (Amontons' 2nd law)
Kinetic friction is independent of the sliding velocity. (Coulomb's law)

The first and second laws, which were founded by Amontons, and the third law, which was founded by Coulomb later, are called the Amontons-Coulomb laws of friction. (These 3 laws only apply to dry friction; the addition of a lubricant modifies the tribological properties significantly.)

The laws are shown by the classic example of a brick resting on an inclined plane, where it is in equilibrium and thus motionless. The force of gravity is opposed by static friction and as the angle of tilt of the plane is increased, the brick will eventually start to move downwards as gravity overcomes the frictional resistance.

Coulomb later found deviations from Amontons’ laws in some cases. In systems with significant non-uniformity of the stress field, because local slip occurs before the entire system slides, Amontons’ laws are not satisfied macroscopically.

Honours

Member, Académie des Sciences (1690)
The crater Amontons on the Moon is named after him.

Notes

Yannick Fonteneau (2011). Développements précoces du concept de travail mécanique (fin 17e s.-début 18e s.): quantification, optimisation et profit de l'effet des agents producteurs (Doctoral thesis) (in French). Université Claude Bernard Lyon 1. p. 572.
Lang, Harry G. (1995). Deaf persons in the arts and sciences: a biographical dictionary. Bonnie Meath-Lang. Westport, Conn.: Greenwood Press. ISBN 0-313-29170-5. OCLC 31374052.
B. Le Bovier de Fontenelle (1705). "Eloge de M. Amontons". Histoire de l'Académie Royale des Sciences: 150.
Amontons, G. (1695), Remarques et expériences physiques sur la construction d'une nouvelle clepsydre, Paris.
Amontons (20 June 1699) Moyen de substituer commodement l'action du feu, a la force des hommes et des cheveaux pour mouvoir les machines (Method of substituting the force of fire for horse and man power to move machines), Mémoires de l'Académie royale des sciences, in: Histoire de l'Académie Royale des Sciences, pp. 112-126.
Chisholm, Hugh, ed. (1911). "Cold" . Encyclopædia Britannica (11th ed.). Cambridge University Press.
"Amontons' engine". hotairengines.org.
"The Stirling Engine". hotairengines.org.
"Ericsson's Caloric Engine". hotairengines.org.
Amontons (19 December 1699) De la resistance causée dans les Machines, tant par les frottemens des parties qui les composent, que par roideur des cordes qu'on y employe, & la maniere de calculer l'un & l'autre (On the resistance caused in machines, both by the rubbing of the parts that compose them and by the stiffness of the cords that one uses in them, & the way of calculating both), Mémoires de l'Académie royale des sciences, in: Histoire de l'Académie Royale des Sciences, pp. 206-222.
Bowden, F.P. & Tabor, D. (1950) The Friction and Lubrication of Solids pp1, 87-89
Dowson, Duncan (1977-10-01). "Men of Tribology: Leonardo da Vinci (1452–1519)". Journal of Lubrication Technology. 99 (4): 382–386. doi:10.1115/1.3453230. ISSN 0022-2305.
washington.edu, Introduction to Tribology - Friction
Popova, E.; Popov, V.L. (2015-06-30). "The research works of Coulomb and Amontons and generalized laws of friction". Friction. 3 (2): 183–190. doi:10.1007/s40544-015-0074-6.
Otsuki, M.; Matsukawa, H. (2013-04-02). "Systematic breakdown of Amontons' law of friction for an elastic object locally obeying Amontons' law". Scientific Reports. 3: 1586. arXiv:1202.1716. Bibcode:2013NatSR...3E1586O. doi:10.1038/srep01586. PMC 3613807. PMID 23545778.

External links

The Galileo Project entry on which this biography is partly based.

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