ROGERS, William Augustus, astronomer, born in Waterford, Connecticut, 13 November, 1832. He was graduated at Brown in 1857, taught in Alfred academy, where he had been prepared for college, and in 1858 was given its chair in mathematics and astronomy, which he held for thirteen years. Meanwhile, during leaves of absence, he passed a year at the Sheffield scientific school of Yale as a student of theoretical and applied mechanics, one year as a special student of astronomy in the Harvard observatory, which was followed by six months' experience as an assistant, and spent fourteen months in the United States naval service during the civil war. The observatory at Alfred was built and equipped by him. In 1870 he was appointed assistant in the Harvard observatory, and he became in 1877 assistant professor of astronomy. In 1886 he was called to the chair of astronomy and physics at Colby university. His special work at the Harvard observatory consisted in observing and mapping all the stars down to the ninth magnitude in a narrow belt, a little north of our zenith. The observations on this work extended over a period of eleven years, and required fifteen years for their reduction. Four volumes of these observations have already been issued, and two more are in preparation. While Professor Rogers has severed his connection with Harvard, he still retains supervision of his unfinished work at the observatory. One of the earliest difficulties that he met with was the finding of micrometer spider-webs that were suitable for his work. After numerous experiments he succeeded in etching glass plates with the moist fumes of hydrofluoric acid so satisfactorily that the United States government ordered the plates, which were used by the expeditions that were sent out from this country to observe the transit of Venus. His study of this subject, extending over sixteen years, has made him a universally acknowledged authority in all that pertains to micrometrical work. He has specially studied the construction of comparators for the determination of differences in length, and has established useful working standards of measurement for practical mechanical work, resulting in the Rogers-Bond universal comparator, built by the Pratt and Whitney company of Hartford. who were thus enabled to make their system of standard gauges, in 1880 he was sent abroad to obtain authorized copies of the English and French standards of length. These were used as the basis of comparison for the bars that he constructed and that now serve as standards of length for Harvard, Yale, Columbia, Princeton, the United States signal service, the Lick observatory, and other important institutions. Professor Rogers's micrometer rulings, both on metal and glass, are known to microscopists for their accuracy as regards divisions, and also for the character and beauty of the lines. In 1880 he was made a fellow of the Royal society of London, and he has since been advanced to the grade of honorary fellow. He was elected in 1885 to the National academy of sciences, and was vice-president of the American association for the advancement of science in 1882-'3, presiding over the section in mathematics and astronomy. In 1886 he was chosen president of the American society of microscopists. The degree of A. M. was conferred on him by Yale in 1880, and that of Ph.D. in 1886 by Alfred university. His published papers, nearly fifty in number, relate to his specialties, and have been published in scientific journals or in the transactions of the learned societies of which he is a member.