Phillips, Edouard

SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

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b. 21 May 1821 Paris, France

d. 14 December 1889 Pouligny-Saint-Martin, France

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French engineer and mathematician who achieved isochronous oscillations of a balance by deriving the correct shape for the balance spring.

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Phillips was educated in Paris, at the Ecole Polytechnic and the Ecole des Mines. In 1849 he was awarded a doctorate in mathematical sciences by the University of Paris. He had a varied career in industry, academic and government institutions, rising to be Inspector- General of Mines in 1882.

It was well known that the balance of a watch or chronometer fitted with a simple spiral or helical spring was not isochronous, i.e. the period of the oscillation was not entirely independent of the amplitude. Watch-and chronometer-makers, notably Breguet and Arnold, had devised empirical solutions to the problem by altering the curvature of the end of the balance spring. In 1858 Phillips was encouraged to tackle the problem mathematically, and two years later he published a complete solution for the helical balance spring and a partial solution for the more complex spiral spring. Eleven years later he was able to achieve a complete solution for the spiral spring by altering the curvature of both ends of the spring. Phillips published a series of typical curves that the watch-or chronometer-maker could use to shape the ends of the balance spring.

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Principal Honours and Distinctions

Académie des Sciences 1868. Chairman, Jury on Mechanics, Universal Exhibition 1889.

Bibliography

1861, "Mémoire sur l'application de la Théorie du Spiral Réglant", Annales des Mines 20:1–107.

1878, Comptes Rendus 86:26–31.

An English translation (by J.D.Weaver) of both the above papers was published by the Antiquarian Horological Society in 1978 (Monograph No. 15).

Further Reading

J.D.Weaver, 1989, "Edouard Phillips: a centenary appreciation", Horological Journal 132: 205–6 (a good short account).

F.J.Britten, 1978, Britten's Watch and Clock Maker's Handbook, 16th edn, rev. R Good (a description of the practical applications of the balance spring).

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