is plainly shown in Greek sculptures antedating the Christian era. Nowadays the sand-glass has pretty much disappeared, except as a kitchen timepiece for boiling eggs and the like. [Illustration] HOUR HAND—The hand of a watch or clock which indicates the hour: for long after clocks were first made, the only hand provided. HOUR WHEEL—The wheel which revolves on the minute wheel or cannon pinion and carries the hour hand. HOWARD, EDWARD—Born at Hingham, Mass., October 6, 1813. Having served a regular apprenticeship in clockmaking he entered into partnership with D. P. Davis, at the age of 29, to make clocks. He was a clever mechanic and invented many pieces of mechanism, among them the swing rest. In 1849 he and Davis with A. L. Dennison and others organized the American Horologe Company for the manufacture of watches by machinery, and with the parts interchangeable—the American principle of today. Though they were not financially successful the American watch industry owes its present day success largely to this beginning by Edward Howard and Aaron L. Dennison. The first company developed into the present Waltham Company, and later Mr. Howard established the E. Howard Co., at Roxbury, but severed his connection with them in 1882 and retired from business. He died March 5, 1904. HUGGEFORD, IGNATIUS—An English watchmaker, one of whose watches was used to defraud Facio of his patent on the use of jewels in watches. See _Facio, Nicolas_. HUNTER, OR HUNTING-CASE—A watch case which has a solid metal cover over the dial. HUNTER, GEORGE—Identified with watchmaking in America since about 1860—in the Waltham and Elgin Companies. He was general superintendent of the latter from 1872 to 1903, after which he was made consulting superintendent. HUYGHENS, CHRISTIAN—A celebrated Dutch astronomer and mathematician born at The Hague, April 14, 1629. Although the honor is claimed for Richard Harris in 1641 and for Vincent Galileo in 1649 it seems historically established that Huyghens in 1657 was the first to apply to clocks the theory of the isochronism of the pendulum which the great Galileo had discovered. In 1669 he published his important work, "Horologium Oscillatorium." In 1673 he made the first clock with concentric hour and minute hands. He died in 1695. HUYGHENS' CHECKS—The arc of a swinging pendulum is a segment of a circle. For perfect isochronism it should be a cycloidal segment. To accomplish this Huyghens fixed curved brass pieces called checks for the cord to strike against but he caused thereby a greater error than he remedied. This end was later accomplished by suspending the pendulum by means of a flat steel strip instead of a cord; a device credited to Robert Hooke. [Illustration] HYPOCYCLOID—A curve generated by any point in the circumference of a circle which is rolled on the inner side of the circumference of a larger fixed circle. [Illustration]