Roy, Julian David Le

, an architect and antiquary, was born at Paris in 1728, and was son of Julian le Roy, a celebrated mechanist, who so excelled in the art of watchmaking, that his time-pieces acquired the same celebrity in France as those of Graham in England. He died at Paris in 1759, at the age of 74, leaving four sons; of whom Julian became an eminent architect, and greatly improved the French style of architecture. He wrote, 1. “Ruines des plus beaux Monumens de la Grece,” which obtained for the author admission into the Academy of Inscriptions. This first appeared in 1758, but many errors having been pointed out by our Athenian Stuart, he published a more correct edition in 1770. 2. “Histoire de la disposition et tiesformes differentes des Temples des Chretiens;” 3. “Observations sur les Edifices des anciens Peuples. 4.” De la Marine des anciens Peuples.“5.” Les Navires des Anciens,“1783, 8vo, and in 1785, another on the same subject; which was followed, in 1796, by a memoir on cutting masts in the Pyrenees. This ingenious man died at Paris in the year 1803, at the age of seventy-five. His brother Peter was watch-maker to the king, and published memoirs for the clock-makers of Paris,” Etrennes Chronometriques,“” Treatise on the Labours of Harrison and le Roy for the Discovery of Longitude at Sea." He died in 1785. The English, on account of their numerous discoveries in this art, had enjoyed such a reputation for the excellence of their clocks and watches, that they found every where a market, in preference to any others, and tbr | French themselves were obliged to come to England for their time-pieces, until Julian le Roy, the father, had the honour of removing, in part, this pre-eminence, and of transferring it to the French. He made many discoveries in the construction of repeating-clocks and watchc- in second and horizontal watches he invented an universal compass with a sight an extremely useful ar.d simple contrivance for drawing a meridional line, and finding the declination of the needle; and a new universal horizontal dial. It is to him we are indebted for the method of compensating for the effects of heat and cold in the balances of chronometers, by the unequal expansion of different metals, a discovery which has been brought by our English artists to a state of great perfection, although it had been thrown aside by the inventor’s son, Peter. 1

1 Dict. Hist. Rees’s Cyclopædia.