HEWITT, Peter Cooper, American capital ist and inventor: b. New York, 1861. He is the• son of Abram S. Hewitt (q.v.) and grandson of Peter Cooper, was educated at Stevens Institute, Hoboken, and Columbia Col lege. He entered business with his father, be came a director of Cooper, Hewitt & Company, and of the Cooper, Hewitt Electric Company, and of several other corporations. He is a trustee of Cooper Union and of the House of Rest, and member of the American Institute of Electrical Engineers, of the Illuminating Engi neering Society, and other learned bodies. He invented improvements in the processes of the Peter Cooper glue factory, which the Hewitt firm controls. Turning his attention to elec tricity he invented the Cooper Hewitt lamp and static converter. The lamp in its present form consists of a glass tube of any desired shape with a bulb at one end which contains a small quantity of mercury. All air is exhausted from the tube, which thereupon fills with vapor from the mercury in the bulb. Electrodes are pro vided at each end of the lamp, the negative electrode in the bulb of mercury and the posi tive electrode at the opposite end. On passing a direct current through the lamp the vapor which fills the tube is rendered incandescent and gives off a steady, blue-white light. Owing to the great resistance at the negative electrode to the initial flow of current, it is necessary to use a high voltage to start the lamp. This is
commonly done by passing a spark from a coil through the negative electrode, which when once penetrated offers but slight resistance to flow of current. If for any reason the current is interrupted, the high re sistance is immediately resumed and must be broken down again before permitting further flow of current. The light given off by this lamp is entirely lacking in red rays, and con sequently does not reveal the real color of the objects it falls upon. It is, however, of great value as a photographic illuminator, being rich in actinic rays, which most affect the photo graphic plate. Mr. Hewitt is investigating with a view to discover means to turn some of the rays of the incandescent vapor into red rays. This discovery will be a means of great econ omy, because the Cooper Hewitt lamp is prob ably the cheapest artificial light in the world. The mercury vapor lamp consumes one-half watt per candle-power, as against three and one-half watts in the incandescent lamp. He invented also a mercury vapor rectifier, which greatly simpli fied the reduction of alternating current to direct storage batteries. Her is also inventor of several mechanical appliances and of an im provement in wireless telegraphy by means of mercury vapor in a vacuum.