Page:Popular Science Monthly Volume 72.djvu/453

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ment of Science, besides having other honorary memberships and degrees in large number.

John A. Brashear began to make telescopes as a business in 1880; although his first telescope, a refractor of five-inch aperture, was made in 1872-5. When it is remembered that Brashear had reached middle life before he relinquished his employment as master mechanic in the rolling mills to begin experimenting in the field of optics and astronomy, the amount of valuable scientific work he has accomplished in the thirty-odd subsequent years is fairly amazing. He made many pieces of apparatus for Professor Langley's studies; besides a long list, impossible to enumerate here, of telescopes, reflecting lenses, mirrors and spectroscopes for astronomers' use in all parts of the world. He has sent instruments to England, Ireland, France, Germany, Egypt, South Africa, Australia, Syria, Italy, Argentina, Japan and numerous other countries, besides an endless series of apparatus for use in the United States and Canada. One reflecting telescope which he himself used in a three years' study of the floor of the lunar crater Plato, was in constant use afterwards by Professor Langley. Brashear developed a highly valuable method of silvering mirrors, which was freely given to the scientific world; published a paper on "A New Method of Correcting Errors of Curvature in Optical Surfaces," which has proved invaluable; constructed apparatus for measuring the velocity of light, and also to measure the differential velocities between long and short waves; many refractometers, and optical trains—among which were two for Lord Rayleigh with error not exceeding 1/1,500,000 of an inch. He constructed the first spectro-photoheliograph for Professor Hale, a work that was epoch-making in the realm of solar photography. One of his spectroscopes made for Professor James E. Keeler, of Allegheny Observatory, was the instrument used by Keeler in the discovery of the physical character of the rings of Saturn, proving the correctness of the Clark Maxwell mathematical theory. One of his finest instruments is the Mills spectrograph for the Lick Observatory, used by Professor Campbell in his many discoveries of the motions of stars in the line of sight. With the cameras he has built for astronomical photography a hundred new planetoids have been discovered. He has made, perhaps, the largest perfect plane in existence, 33-inch diameter. He has just completed the 37½-inch mirror of the great Cassegrain telescope for the University of Michigan; and is now constructing a 30-inch refractor for the Allegheny Observatory and a 24-inch for Swarthmore; and has orders for enough large and important instruments to tax the capacity of his workshop for more than two years.

Data about the hundreds of pieces of apparatus that he has made would fill a book. And besides, he has raised by his own personal efforts nearly three hundred thousand dollars for the construction of