( 244 ) 



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 dif- 

 ferent forms. Sometimes they consist merely of frozen drops 

 of rain, unaccompanied by any extraordinary appearances ; and 

 are easily accounted 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 mysterious causes we are now desirous of 

 penetrating, the hailstones are of great and sometimes enor- 

 mous size, and are associated with the most impressive and sub- 

 lime phenomena of nature. 



To pass over many statements on record of hailstones of a 

 magnitude almost surpassing behef -f-, we have authentic state- 

 ments of such as exceeded one foot in circumference \, 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 

 iournals, and in the transactions of learned societies. After 

 comparing a great number of these descriptions of hail storms, 

 the following propositions appear to me to embrace the most im- 

 portant facts. 



1. Hail storms, when violent, are characterized by 



THE meeting of ALL THE ELEMENTS OF STORMS ; the clouds 



are very black ; they are strongly agitated, and fly swiftly 

 through the air, or more frequently rush towards each other, 

 attended by high winds and terrific thunder and lightning §. 

 % Hail storms, of the foregoing character, are con- 



• Silliman's American Journal of Science. 



-|- 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 ; af- 

 ter which the clouds broke into thunder and lightning, and there fell hail- 

 stones of one hundred pounds weight. (Encyc. Perth. II, p. 14). 



+ Halley, Phil. Trans. § Phil. Trans, vols. iv. and v. 



