the Theory of Hail. 181 



earth. When we consider the enormous amount of water 

 which is rapidly carried up in a tornado, and that the lower 

 part of the region of freezing must contain mostly rain not 

 yet frozen, since the snow there formed is at once carried still 

 higher, we can readily understand how the hailstone can re- 

 ceive a considerable coating of ice in a short time. While 

 high up in the snow-cloud at its turning point, it of course 

 remains some time nearly at the same altitude, and it is 

 reasonable to suppose long enough to receive its coating 

 of snow 30 . 



Hailstones vary greatly in shape as well as in weight, 

 Some resemble a disk, or very oblate spheroid. If for any 

 reason the hailstone becomes in the least flattened, the ascend- 

 ing current which keeps it suspended in the air also keeps its 

 shortest diameter perpendicular to the current, and hence it 

 increases most on the edges. Others are of a pyramidal 

 form 31 . 



Enormous masses of ice are reported to have fallen from 

 the sky from time to time, but these seem to have consisted 

 of a vast number of hailstones swept into hollows or 

 cavities by the wind, and united by regulation. Nevertheless, 

 some of the masses that are known on good authority to have 

 fallen are sufficiently formidable. Mr. Darwin 32 refers to 

 cases in South America of hailstones sufficiently large to kill 

 deer, and many cases are recorded of hailstones in India 

 large enough to kill men and cattle 33 . The hailstones chiefly 

 occur in the driest months, February, March, and April ; 

 they are well known in the Delta of the Ganges down to the 

 sea, in other places 1500 feet above the sea ; in Ceylon the 

 storms are formed by violent whirlwinds and eddies. Thus 

 on May 12th, 1853, a storm occurred in the Himalayas, 

 when the hailstones were very hard, compact and spherical, 



30 In a hailstorm at Northampton, Mass., June 20th, 1870, two hail- 

 stones fell weighing over half a pound. One is described in Silliman's 

 Journal 1. p. 403, consisting of thirteen layers, like the coats of an onion. 

 It must have oscillated as many times between the rain-cloud and the 

 snow-cloud region ; that is, it performed six or seven revolutions with 

 the lower part of its orbit in the rain-cloud, and the upper part in the 

 snow-cloud. 



31 On this subject see a paper by Professor Osborne Reyuolds on 

 Raindrops and Hailstones in ' Nature,' Dec. 21st, 1876. 



32 Journal of a Naturalist. 



33 See a paper by Dr. George Buist, F.H.S., on Hailstorms in India, 

 read before the British Association in 1885. The writer corrects the 

 statements of Dr. Purdie Thompson and others that hailstorms are nearly 

 unknown between the tropics. 



Phil. Mag. S. 5. Vol. 28. No. 172. Sept. 1889. P 



