Hands—The metal pointers which, moved by the train, indicate the time by pointing to the figures on the dial. At present there are always two, the hour and minute hands and frequently a seconds hand also. Clocks at first were made with only the hour hand; the minute hand was introduced when the use of the pendulum made timekeeping sufficiently accurate for the indication of such small divisions.
Hanging Barrel—A going-barrel with its arbor supported only at the upper end.
Harris, Richard—An English clockmaker for whom it is claimed that he made the first pendulum clock—set up at St. Paul's, Covent Garden, in 1641. Most authorities agree, however, that this honor belongs to Huyghens.
Harrison, John—An English mechanician born at Faulby in Yorkshire in 1693. He made many improvements in the mechanism of clocks, the greatest of which was the compound pendulum. He won in 1761 a reward offered by Parliament in 1714 for an instrument that would determine longitude within thirty marine miles. Harrison's chronometer gave it within eighteen miles. He invented the going fusee, the gridiron compensation pendulum and suggested the idea for the compensation balance, afterward worked out by other watchmakers. Died 1776.
Hautefeuille, John—(Abbe.) Born 1647. Died 1724. He disputed successfully Huyghens' claim to a prior invention of the steel balance spring. He is also credited with the invention about 1722 of the rack-lever escapement.
Heart-Piece—The heart-shaped cam on the center-seconds wheel of a chronograph, which causes the hand to fly back to zero.
Hele, Peter—(See Henlein, Peter.) Some historians credit invention of first watch to Peter Hele. There is no doubt, however, that Hele and Henlein were one and the same. Preponderance of authority favors "Henlein" as the correct spelling of the name.
Helical—Following the course of a helix or spiral.