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SKETCH OF DENISON OLMSTED.

light to substantially the same origin. These views, however, as Prof. Silliman observes, were mostly thrown out only as conjectures, and not as formal theories to be held and defended.

Previous to this. Prof. Olmsted had interested himself in meteorological studies. In 1830 he published in the American Journal of Science a new theory of hailstones, in which he ascribed the origin of those formations to the sudden mingling of large bodies of hot and humid air with air extremely cold, by which the vapor of the former would be rapidly condensed and congealed into hail. These effects, he assumed, would be produced whenever, by means of opposing winds, whirlwinds, or other atmospheric disturbances, hot air should be brought above the line of congelation or cold air brought below it.

He agreed with Redfield in supposing that ocean gales are progressive whirlwinds; and he believed that he had established their laws or modes of action on an impregnable basis. This view of storms as progressive whirlwinds still holds good as a generalization; but his further ascription of the ultimate causes of atmospheric disturbances to the diurnal and orbital motions of the earth has not found an accepted place in science. Prof. Olmsted had a close friendship and a warm sympathy with Mr. Redfield, with whose views respecting the rotatory motions of storms he agreed; and he read an affectionate memorial of him before the American Association, at Montreal, in 1857.

Prof. Olmsted and Prof. Loomis, who was then a tutor in the college, were the first persons of all observers to find Halley's comet on its return in 1835. One of the results of this observation was the awakening of an interest in procuring larger and improved telescopes. It did not bring immediate fruit, it is true. The project already conceived for the establishment of a permanent observatory at Cambridge, to which it gave a new impulse, was not yet to be made real. There were other circumstances, however, than want of interest in astronomy that kept such liberal schemes from being carried out—the country and the universities had not grown up to them, and the needed abundance of money had not yet come—but this was one of the incidents that kept the movement vital and sped it on. Prof. Olmsted also conceived a plan for the establishment of an observatory at Yale College, which should have two departments: one to aid in the instruction of students and the other for the use of scientific observers; but the time had not yet come for this. As another incident of his astronomical work. President Woolsey relates that "for a number of years, until his health forbade it and his eyesight began to fail, he was accustomed to gather his class around him on a bright autumn evening and introduce them to the heavenly bodies. In this way he endeavored to train up a