Prof. Loomis on the Hail Storm of the first of July, 1853. 49 
In a vacuum, a body falling under the influence of gravity is 
continually accelerated ; but when aheavy body falls through 
the atmosphere, the resistance increases with the velocity, until 
the resistance becomes equal to the weight of the body. When 
this takes place, there can be no further increase of velocity, and 
the body will afterwards descend with a uniform motion. In or- 
der therefore to determine the greatest velocity which a heavy 
body ean acquire by falling through the atmosphere, it is only 
necessary to compute the weight of a sphere of given diameter, 
and then to search in the preceding table for the velocity due to 
an equal resistance upon a body of the proposed diameter. ‘The 
following Table exhibits the results for spheres of lead (assuming 
the specific gravity 11:35), of iron (specific gravity 7-78), of wa- 
ter, of ice (sp. gr. 0-93), and cork (sp. gr. 0:25); the diameters 
varying from two inches to one-eighth of an inch. 
Weight of a sphere of Final velocity of sphere of 
: Lead. Tron. | Water.| Ice. | Cork. }) Lead. |Iron.| Water.) Ice.jCork 
Diam. | ounces. | ounces. | ounces. { oun es.| ounces.| feet. | feet.) feet. /feet. feet. 
2 in | 27°5182| 188593 24241 | 22544 | 06060 | 810 |257/- 94 | 90| 47 
1 “ } 34392) 23574 | 03030 | 02818 | 0:0757 | 293 |185/ 68 | 65 | 384 
+ “ | 04299} 02947  0-0379 | 0-:0352 | 00095 | 161/134! 49 | 47) 25 
t “ | 00537! 00368 0-0047 | 0-0044 | O-0012 | 117 97| 36 | 85| 18 
$ “ } 00067| 00046 0-0006 | 00006 |.0:0001 1 84 | 70) 25 | 24| 19 
hus it appears that a hail stone in the form of a sphere two 
and would greatly reduce the velocity of stones of larger size, 
The Strong upward movement which is known to exist in the 
neighborhood where hail is formed, is therefore quite sufficient to 
Sustain hail stones of the largest kind as long as they can be kept 
within the influence of this vortex. After they have entirely 
*scaped from the influence of the vortex, small stones would fall 
fo the earth from an elevation of 5000 feet in about two min- 
ules ; and very large stones in one minute. I see no difficulty 
cases, stones may remain supported for ten minutes and even a 
Steat deal longer. This period appears to me sufficient to ac- 
“ount for the hail which fell at New York. : ae Ws “oe 
Steonp Senims, Vol. XVII, No, 49.—Jan,, 1854... ia 
