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.
IDLER, IDLE WHEEL, OR INTERMEDIATE WHEEL—A toothed wheel used to connect driver and follower wheels so that both shall rotate in the same direction.
IMPULSE—The push transmitted to the pallet by the escape wheel.
IMPULSE PIN—The jewel pin—usually a ruby—on the table roller of the lever escapement, which playing into the fork of the lever transmits the impulse to the balance.
INDEPENDENT CENTER-SECONDS—A watch peculiarly adapted to the use of the medical profession. It carries on a separate train a long seconds hand in addition to the hands of the ordinary watch which can be stopped without stopping the watch.
INDEPENDENT SECONDS—A watch whose seconds hand is driven by a separate train.
INGERSOLL, CHARLES HENRY—Secretary, Treasurer and General Manager of Robt. H. Ingersoll & Bro., watch manufacturers, of New York City. Born at Delta, Eaton County, Michigan, October 29, 1865, a son of Orville Boudinot and Mary Elizabeth (Beers) Ingersoll. At the early age of fifteen years he left home and went to New York City, where he entered the employ of his brother, Robert H., who was then engaged in the business of manufacturing rubber stamps. Since 1880 he has been continuously associated with his brother in various business enterprises and in the direction and management of the Ingersoll organization. Married Eleanor Ramsey Bond of Brooklyn, New York, July 5, 1898. Residence, South Orange, New Jersey.
INGERSOLL, ROBERT HAWLEY—Founder and President of Robt. H. Ingersoll & Bro., watch manufacturers, of New York City. Born December 26, 1859, of Orville Boudinot and Mary Elizabeth (Beers) Ingersoll, at Delta, Eaton County, Michigan, he received his early education in the public schools of his native town. In 1879, at the age of nineteen years, he came to New York City, and in the following year engaged in the business of manufacturing rubber stamps; later, he established a mail order business, selling various "dollar" specialties and novelties. While engaged in this business he conceived the idea and in 1892 commenced the manufacture of the "dollar watch," since which time over 50,000,000 watches have been produced and sold by the Ingersoll organization. Married June 20, 1904, to Roberta Marie Bannister of Green Bay, Wisconsin. Residence, Oyster Bay, Long Island.