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ONE of the most striking illustrations of the value and range of man's reasoning faculty is afforded by the substantially simultaneous calculation, on a purely mathematical basis, of the elements of the then unseen and unknown planet Neptune, and the prediction of the place in the sky where it would be found on a given day, by the Englishman Adams and the Frenchman Leverrier. While Leverrier succeeded in first attracting public attention to his work, Adams anticipated him in beginning the calculation and in bringing it to a satisfactory result.

Prof. J. W. S. Glaisher treats Adams's first paper, by means of which the new planet might have been discovered, as furnishing the final and inexorable proof of Newton's law of gravitation; and the day when it was taken to Greenwich—October 21, 1845—as therefore marking a distinct epoch in the history of gravitational astronomy.

John Couch Adams was born at Lancast, seven miles west of Launceston, Cornwall, England, June 5, 1819, and died at the observatory in Cambridge, January 21, 1892. His father was a tenant farmer; his mother had a small landed estate of her own, and had inherited her uncle's library, in which were a few books on astronomy. He was interested in these books, and made rapid progress at the village school, and was learning algebra before he was twelve years old, at which age he went to a private school at Devonport, where he had Mr. Grylls, a cousin of his mother's, as his teacher. While he studied, as usual, the classics and mathematics, astronomy was his favorite branch, and he was making notes and drawing maps of the constellations when fourteen years old; he read eagerly all the astronomical books he could find, and soon became interested, by the perusal of Vince's Fluxions, in the higher mathematics. In 1837 it was contemplated to send him to the University of Cambridge; in October, 1839, he entered St. John's College of that university. During his undergraduate career, according to Prof. J. W. L. Glaisher, he was invariably the first man of his year in the college examinations. In 1843 he was graduated as senior wrangler, being also first Smith's prize-man. The occurrence of a small constellation of mathematical senior wranglers at Cambridge about this time is noted in one of the biographies of Adams, viz.: Stokes in 1841, Cayley in 1842, and Adams in 1843—all three of whom have since been professors, and famous. Adams was elected a Fellow of his college on the year of his graduation, and continued in that relation till 1852, when, he not having taken holy orders, his fellowship ex-