Brashear, John Alfred

Updated About encyclopedia.com content Print Article Share Article
views updated

Brashear, John Alfred

(b. Brownsville, Pennsylvania, 24 November 1840; d. Pittsburgh, Pennsylvania, 8 April 1920)

astrophysical instruments.

Until 1881 John Brashear was a mechanic in a Pittsburgh steel mill by day and an amateur telescope maker by night; then, through the encouragement of Samuel Pierpont Langley and with the financial support of William Thaw, he was able to establish a workshop for making astronomical and physical instruments. During the next half century the John A. Brashear Company produced many of the major instruments used throughout the world for astrophysical research. In 1926 the Brashear concern was bought by J. W. Fecker of Cleveland, Ohio.

Besides a dozen or so workmen and “Uncle John”, as he was widely and affectionately known, the Brashear Company employed two notable “associates”: Charles Sheldon Hastings, an optical physicist at Yale University, and James McDowell, Brashear’s son–in–law. Hastings computed the curves of most of the objective lenses figured in the Brasher shops, and McDowell did most of the actual optical work.

The Brashear Company began at an opportune time: establishing large and well–equipped astronomical observatories had recently become an acceptable philanthropy; and astronomers, beginning to study the quality and quantity, as well as the position, of starlight, needed new types of instruments. Since most other astronomical instrument makers concentrated on equatorial refracting and reflecting telescopes or apparatus for terrestrial and celestial surveying, Brashear, who was adept at producing special–purpose instruments, had few competitors.

Among Brashear’s astronomical contributions were an improved and soon widely used process for silvering glass mirrors; the concave metal mirrors on which Henry A. Rowland ruled diffraction gratings; spectroscopes for use with the large refractors at the Allegheny, Lick, Princeton, and Yerkes observatories; George Ellery Hale’s first spectroheliograph for photographing solar prominences; the optical parts of the interferometer with which Albert A. Michelson measured the standard meter; a 16–inch–aperture, double–photographic doublet for Max Wolf at Heidelberg; and numerous telescope objectives—both lenses and mirrors—culminating in the 72-inch-aperture primary mirror for the Dominion Observatory in Canada.

BIBLIOGRAPHY

The best original sources for an instrument maker are the instruments themselves; and the best secondary sources are the articles about the instruments and the work done with them published in scientific journals and in observatory annals.

I. Original Works. Brashear wrote many short articles, frequently describing his techniques and work in progress, which were published in most of the contemporary astronomical journals; the first, “Hints on Silvering Specula, Periscopic Eyepieces, & c…” appeared in English Mechanic, 31 (1885), 327. Also of value is his The Autobiography of a Man Who Loved the Stars (Boston, 1925).

II. Secondary Literature. Among the numerous published accounts of Brashear’s life that stress his many educational and philanthropic activities, mention may be made of J. S. Piaskett, “James B. McDowell, an Appreciation,” in Journal, Royal Astronomical Society, Canada, 18 (1924), 185–193; and Frank Schlesinger, “John Alfred Brashear, 1840–1920”, in Popular Astronomy, 28 (1926), 373–379.

Deborah Jean Warner