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.P;j Indian Hqil-storms, By A. Turnbull CuRi,sTi^e, M. D. 

 ,^^r. r - T* ■ Communicated by the Author. 



In the 'last Number of your Journal, a new theory of hail- 

 storms is proposed by Professor Olmsted of Yale College, viz. 

 that they are caused by " the congelation of the watery vapour 

 i!)f a body of warm and humid air, by its suddenly mixing with 

 an exceedhigly cold wind in the Jiigher regions of the atmo- 

 sphere." 



i^' According to this theory it is v#y easy to account for those 

 "fiail-storms which so frequently occur in some parts of the tem- 

 'perate zones, as in the south of France, or in the United States 

 of America ; for in such situations it is very possible that an 

 intensely cold wind, proceeding from the north at a great height, 

 inight meet with a warm body of air highly charged with mois- 

 ture, and thus cause a very sudden congelation, with the other 

 phenomena that generally accompany such storms. But this 

 explanation could not apply (even according to the Professor's 

 own showing) to hail-storms in the torrid zone, for any two cur- 

 irents of air, within this zone, would differ so little in tempera- 

 ture, that their sudden mixture could not possibly produce con- 

 gelation, but merely clouds and rain, thunder and lightning; 

 and, says the Professor, " in this region we know not where to 

 •took for the freezing current, unless we ascend so high that 

 diere no hot air exists holding watery vapour to be frozen by 

 it.'' He therefore supposes that violent hail-storms are unknown 

 In the torrid zone, excepting in one situation, viz. in the vici- 

 nity of lofty mountains covered with snow. Here, however, he 

 is mistaken, hail-storms being by no means uncommon in differ- 

 ent parts of the peninsula of India, and consequently at a dis- 

 tance of many hundred miles from any lofty mountains *. 

 ' We are told, in Rees's Cyclopaedia, that hail-storms never 

 pccur in the torrid zone ; and in the Edinburgh Encyclopaedia, 



. svfiftrhe highest mountains in the peninsula of India are the Neelgherries, 

 A small group, situated between the 10th and Hth degrees of north latitude, 

 and having a height of little more than 8000 feet'above the level of the sea, 

 ^eing not more than one^half of that which the snow-line would have in this 

 fcituatlon. 



