HAIL STORMS. 341 



It is also certain, that a vacuum must be 

 formed in the lower atmosphere proportional to 

 the volume of vapour thus suddenly condensed ; 

 the extent of which may be estimated from the 

 vast quantities of hail that are occasionally pre- 

 cipitated in a few minutes, amounting to a depth 

 of nine inches in as many minutes, according to 

 M. Pouillet. The formation of such vacuums is 

 always attended by a rush of air from opposite 

 quarters, creating a gyratory or whirling motion, 

 the force of which is in proportion to the extent 

 of the vacuum and the rapidity of its formation. 

 That the reader may perceive the more readily 

 how intimate is the connexion between lightning, 

 the condensation of vapour, hail storms, and 

 whirlwinds, it may be proper to present a brief 

 account of a few thunder storms which occurred 

 recently in Great Britain : 



On the I Oth of August, 1 835, Durham was visited 

 by a violent whirlwind, accompanied with inces- 

 sant lightning and thunder. At 7 o'clock, p. M. a 

 most vivid flash of lightning struck the Cathe- 

 dral, and hurled down an immense mass of stone, 

 that killed two of a party of students, who at the 

 moment fled from the interior of the Cathedral. 



" On the same day Chesterfield was visited 

 by a violent storm of thunder, lightning, rain, 

 and hail. A large ball of fire fell in the Com- 

 mercial-inn yard, where there was an accumula- 



