Heliotropion—See "[Polos]."
Hemicycle—Form of sun-dial in which the shadow of a vertical pointer or "gnomon" is cast upon and moves around the inner surface of a half globe or sphere. Supposed to have been invented about 350 B. C. (See [Sun-Dial]). Vitruvius, the Roman Engineer, ascribes invention to the Babylonian priest and astronomer, Berosus.
Henlein, Peter—Sometimes called Peter Hele. A clockmaker of Nuremberg, who is believed to have made the first portable (pocket) clock or watch sometime early in the sixteenth century. Born 1480. Died about 1540. His clock was round, driven by a spring and had small wheels of steel. It was much larger than present day watches.
Hollow Pinion—A pinion bored through the center. The center pinion in many watches is hollow.
"Hon-Woo-Et-Low" or Copper Jars Dropping Water—A form of clepsydra at Canton, China, said to be between 3000 and 4000 years old. It consists of four copper jars arranged on steps. Each jar drops water into the one below it until the last one, in which a bamboo float, indicates the time in a rude way.
Hooke, Robert, M. D.—An English physician-philosopher born on the Isle of Wight in 1635. His accomplishments were numerous. He claimed to have discovered the isochronism of the balance spring and its application to watches, though this was also claimed by Huyghens. He invented a pendulum timekeeper for finding the longitude at sea; devised the first wheel-cutting engine about 1670; and he invented the anchor escapement for clocks. His studies and inventions covered a wide field. He died in 1702.
Horologe, (Orologe), (Horologium)—A general term applied indiscriminately in old writings to any mechanism for measuring time.
Horological Institute—British—An association of watchmakers founded in 1858 for the purpose of advancing the horological arts.
Horological Periodicals, American—American Jeweler, (Monthly), Chicago, Ill.; Goldsmith and Silversmith, (Monthly), New Haven, Conn.; Jeweler's Circular, (Weekly), New York,; Keystone (Monthly), Philadelphia, Pa.; Manufacturing Jeweler, Providence, R. I.; Mid-Continent Jeweler, Kansas City, Mo.; National Jeweler, (Monthly), Chicago, Ill.; Northwestern Jeweler, St. Paul, Minn.; Pacific Goldsmith, (Monthly), San Francisco, Cal.; Trader and Canadian Jeweler, Toronto, Canada.
Horologium—See [Horologe].