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by M. Peltier, that Dr. Hare's hypothesis was defective in not 

 taking into account other co-operating forces, as well as those 

 of electricity, was incorrect. 



Dr. Hare made some observations on the effect of the rare- 

 faction of air, on its desiccation and refrigeration, and on other 

 phenomena connected with the presence of aqueous vapour in 

 the atmosphere. He also detailed some experiments, showing 

 that the phenomena of air, heated by re-entering a receiver 

 partially exhausted, were more consistent, in some respects, 

 with the idea that a vacuum has a capacity for heat, than that 

 it is destitute of any appropriate portion of caloric. 



Dr. Hare adverted to the fact, that in an essay, published in Silli- 

 man's Journal in 1822, he had, agreeably to the authority of Dalton 

 and Davy, stated, that the cold consequent on the rarefaction of air 

 in its ascent towards the upper strata of the atmosphere, was one of 

 the causes of the formation of clouds; and in bis text books he had 

 soon after published an engraving of an apparatus, by means of which 

 he was accustomed to illustrate, before his pupils, the transient cloud 

 which arises from a diminution of pressure in air containing aqueous 

 vapour. 



In the essay above mentioned, Dr. Hare had alleged, that as 

 much caloric was given out by aqueous vapour, during its conver- 

 sion into snow, as would be yielded by twice the weight of red-hot 

 powdered glass. But Mr. Espy, he considered, had the merit of being 

 the first to suggest, that the heat, thus evolved, might be an important 

 instrument in causing a buoyancy tending to accelerate any upward 

 current of warm moist air. 



Dr. Hare had been willing to admit, that this transfer of heat might 

 co-operate with other causes in the production of storms, but could 

 not concur with Mr. Espy in considering it competent to give rise to 

 thunder gusts, tornadoes, or hurricanes. These he had considered, 

 and still considers, to be mainly owing to electrical discharges be- 

 tween the earth and the sky; or between one mass of clouds and 

 another. 



With a view to a more accurate estimate of the comparative influ- 

 ence of rarefaction and condensation, in causing evolution of heat in 

 dry air, and in air replete with aqueous vapour, Dr. Hare had per- 

 formed a number of experiments, of which he proceeded to give a 

 description. 



