THE WHITER PITTSBURGH 449 



merit of Science, besides having other honorary memberships and de- 

 grees 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, impos- 

 sible 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 con- 

 stant 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 Correct- 

 ing Errors of Curvature in Optical Surfaces," which has proved inval- 

 uable; 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 Eayleigh 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 Ob- 

 servatory, 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 37%-inch mirror of the great Cassegrain telescope for 

 the University of Michigan; and is now constructing a 30-inch re- 

 fractor 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 



vol. Lxxn. — 29. 



