DENISON OLMSTED. 



257 



has not yet satisfied itself concerning the nature of this phe- 

 nomenon. He also studied the aurora borealis, concerning 

 which he contributed articles to the American Journal of Sci- 

 ence in 1835 and 1837, and gave at length a theory of cosmical 

 origin and secular period in the eighth volume of the Smith- 

 sonian Contributions to Knowledge. He thus ascribed shoot- 

 ing stars, auroras, and the zodiacal 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 as- 

 cribed the origin of those formations to the sudden mingling 

 of large bodies of hot and humid air with air extremely cold, by 

 which the vapour of the former would be rapidly condensed and 

 congealed into hail. These effects, he assumed, would be pro- 

 duced whenever, by means of opposing winds, whirlwinds, or 

 other atmospheric disturbanqes, 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 sci- 

 ence. Prof. Olmsted had a close friendship and a warm sym- 

 pathy with Mr. Redfield, with whose views respecting the rota- 

 tory 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 Hal- 

 ley'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 estab- 

 lishment 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 astrono- 



