46 Prof. Loomis on the Hail Storm of the first of July, 1853. 
What was the cause of the hail? 
The hail was caused by a violent upward movement of the air, 
carrying along with it an unusual amount of vapor, which was 
suddenly condensed, and at so low a temperature, that it was 
frozen in large semi-crystalline masses. 
That there was a violent upward movement of the air, I infer — 
from the following considerations. 
1. Rev. J. W. McLane of Williamsburgh was in the street near — 
his house, and noticed the coming up of the storm. He says the 
cloud was very dense and black—moved rapidly forward—and — 
under the main sheet, the clouds boiled up in a violent and angry 
manner, which led him to anticipate a severe blast. Other ob- 
servers have testified to substantially the same facts. 
It appears impossible that two currents, in close juxta-posi- 
tion, should blow from nearly opposite quarters, with sufficient 
violence to prostrate large trees, unless there is opportunity for the 
air to escape by an upward movement. ‘This conclusion is also 
in perfect harmony with what we have frequent occasion to ob- 
serve in small sand whirls and water spouts. 
How was the cold which formed the hail produced ? 
According to the observations of Pouillet, in France, the tem- 
perature of hail-stones when they fall, is sometimes as low as 25° 
Fahr. They must then have been formed ata temperature con 
siderably below that of melting ice—a temperature probably as 
low as 20° Fahr. How can so low a temperature be produced in 
the hottest weather of July? The temperature of the air dimin- 
ishes as we ascend from the earth, and at the height of 8800 feet 
above New York, is estimated at 32° in summer. At the height 
of 12000 feet the temperature is reduced to 20°. Were the hail 
stones in the present case, formed at an elevation of 12000 feet? 
It does not appear to me that we are at liberty to make such an ~ 
assumption. In the summer of 1835, several hail-storms passed 
over the southern part of France, where there were insulated 
peaks of mountains, which afforded precise means of measuring 
the. elevation of the hail. In the storm of July 28th, 1835, no hail 
fell on the summit of the Puy du Dome, an elevation of 4800 feet 
above the sea; but a few stones fell at the height of 3700 feet, 
while at the foot of the mountain, the ground was covered to the 
depth of three inches, and some of the stones weighed eight 
ounces. On the 2d of August of the same year, a hail cloud en- 
veloped the summit of the mountain, rising therefore to the height 
of at least 5000 feet. 
It does not therefore appear to me that we are at liberty to as 
sume that the hail of July Ist, was formed at an elevation much 
exceeding 5000 feet, and here the summer temperature may )é 
estimated at 46°. This cold is of course insufficient to form ice 
