Julien Le Roy，61 x 81 mm，約 1750
Julien Le Roy, 61 x 81 mm, circa 1750
An important rare equatorial sundial
Case: silver. The geographic latitude of the observation point is set to the scale on the side. In connection with the magnetic compass the instrument is aligned to the north-south direction and the declination. The thread projects the position of the sun on the dial engraved with Roman and Arabic numbers. One is getting the true local time. On the backside of the ground-plate are engraved the geographical declinations from several European towns.
"Cadran Universel e a Mèridienne - Fait et inventé par julien le Roy"
This is not one of the so-called "butterfly" watches that were popular during that period but a rare sun dial created by the ingenious maker Julien Le Roy.
Julien Le Roy (1686-1759)
He was one of the most outstanding clock- and watchmakers of his time and certainly played a decisive part in establishing the leading role French clockmaking had in the 18th century. He became a master in 1713, presented an equation clock to the Académie Royale des Sciences in 1717, and was appointed clockmaker to the king in 1739 (with his own rooms at the Louvre). Le Roy invented the adjustable bracket for the verge escapement wheel ("potence"), the repetition strike on springs instead of bells for pocket watches, and the "all-or-nothing" piece for repeating watches. His inventions and improvements were of such extreme importance that most watchmakers adopted them promptly for their own pieces. Later Le Roy was director of the Société des Arts; he and his son supplied the entries on watches and clocks in the encyclopaedia compiled by Diderot and d'Alembert.