THE 



AMERICAN 



JOURNAL OF SCIENCE, &c. 



Article I. — Of the Phenomena and Causes of Hail Storms. 

 By Denison Olmsted, Professor of Mathematics and Natural 

 Philosophy in Yale College. 



Showers of hail present themselves to us under two very different 

 forms. Sometimes they consist merely of frozen drops of rain, un- 

 accompanied by any extraordinary appearances ; and are easily ac- 

 counted for, by supposing that the air happens at that time to be 

 colder than the region of the clouds, and that the drops of rain are 

 congealed in falling through it. But in those storms, whose mys- 

 terious causes we are now desirous of penetrating, the hail stones 

 are of great and sometimes enormous size, and are associated with 

 the most impressive and sublime phenomena of nature. 



To pass over many statements on record of hail stones of a mag- 

 nitude almost surpassing belief,* we have authentic statements of such 

 as exceeded one foot in circumference, f and those larger than a 

 hen's egg are of yearly occurrence. 



To account for these extraordinary hail storms, is considered as 

 one of the most difficult problems in meteorology. There is little to 

 be found on this subject in systematic works ; but the accounts of the 

 facts lie scattered up and down in scientific journals, and in the trans- 

 actions of learned societies. After comparing a great number of 

 these descriptions of hail storms, the following propositions appear to 

 me to embrace the most important facts. 



* It is related, that during the wars of Lewis the XII, in Italy, in 1510, there was 

 for some time a horrible darkness, thicker than that of night ; after which the clouds 

 broke into thunder and lightning, and there fell hail stones of one hundred poundi 

 weight. (Encyc. Perth. II, p. 14.) t Halley, Phil. Trans. 



Vol. XVIII.— No. I. 1 



