JACQUEMARTS—Figures of man and woman which struck the hours on the clock set up by Philip of Burgundy at Dijon, prior to 1370. G. Peignot says they are so named from Jacquemart, a clock maker of Lille, employed by the Duke of Burgundy in 1442. The lack of co-ordination in the dates tends to controvert the claim. JEROME, CHAUNCEY—Originator of the one-day brass clock movement which enormously increased the American clock business and opened a market for American clocks in Europe. Born in Canaan, Connecticut, in 1793. Established the Jerome Clock Company at New Haven, Connecticut. This was the predecessor of The New Haven Clock Company. JEWELLED—Fitted with precious stones to diminish wear as distinguished from precious stones for ornament. In the best watches ruby and sapphire are used. In lower grade watches quartz, amethyst and garnet. JEWELS—Used in watches as bushings at the ends of pivots and in other places which sustain much wear. They: 1. Provide smooth bearings for the pivots. 2. Obviate corrosion. 3. Reduce the wear from abrasion. Sapphire is the best of the jewels in use and ruby second. Chrysolite is also used and garnet, tho the latter is too brittle for most service. This use of jewels was invented by Nicolas Facio—a Swiss watchmaker about 1705. JULIAN PERIOD—A period of 7980 years obtained by multiplying 28, 19 and 15—the numbers representing the cycles of the sun and moon, and the Roman Indiction. It will end 3267 A. D., until which time there cannot be two years having the same numbers for three cycles. JURA MOUNTAINS—A watchmaking center in Switzerland. The industry grew rapidly following the success of Daniel Jean Richard in 1679. This section is the center of the system of watch-manufacturing most nearly like the American system. See _Geneva_. JURGENSEN, JULES—One of the most famous watchmakers of the 19th century; a son of Urban Jurgensen, born in 1808. He studied physics, mechanics and astronomy in Paris and London and finally settled in Locle, Switzerland, specializing in pocket chronometers, which have become famous as the Jurgensen watches. He died in 1877; and was succeeded by his son, Jules F. U. Jurgensen. JURGENSEN, URBAN—A Danish mathematician and watchmaker born in 1776. He practiced his trade for a time in Switzerland, worked in Paris under Breguet and Berthoud, and then in London, before returning to Copenhagen to enter into partnership with his father, the court watchmaker. He was made superintendent of all the chronometers of the Danish navy and received several decorations. He died in 1830. KEW OBSERVATORY—The central meteorological observatory of the United Kingdom. Established at Richmond in 1842 and afterward transferred to the Royal Society. Since 1900 it has been a department of the National Laboratory. Important to the watch business because of the famous Kew tests of timekeepers and awards for accuracy of performance.