Le Roy - Pierre, son of Julien, Paris
1748: juré, (the word juré is used to indicate the officer of the corporation charged with the duty of inspecting work and workshops, in all the corporations, exept that of London. In Paris, the officer was called at different periods 'juré' 'gardevisiteur' and 'syndic'. In London, the equivalent 'warden' or 'Warden of the Clockmakers Company' is used.
The most eminent horologist of France;
pioneer, with BERTHOUD, of chronometer development in France.
First to apply temperature compensation to the balance.
Devised a duplex escapement with single balance.
In 1748 showed the Academie des Sciences a detent escapement
It was applied to a chronometer in 1766.
His first marine chronometer tried 1763.
Published 'Mém. pour les Horlogers de Paris,' 1750, and 'Étrennes chronométriques pour l'année 1760.'
His inventions are described in Mém. de l'Acad. des Sci. 1742, 1751, 1752, 1755, 1763, 1769, and in Gallon, 'Machines et lnventions,' Vols. V and VII.
He wrote a memoir on time measurement at sea, which gained the prize of the Acad. des Science in 1770, and other memoirs on marine chronometers. Many fine watches and clocks.