West and North-west Winds of New-England. 311 
This, however, was not the fact, even for a moment. Of 
course, during this part of its progress, the south-west wind 
blew beneath the cloud: while that which drove the cloud, 
blew, in the first part of its progress, only ina superior re- 
gion ; and did not strike the earth, until it came near to 
the sound. ‘These phenomena, so far as concerns this sub- 
ject, I saw several times repeated during my residence in 
Greenfield. Nor have I a doubt, that this is the most usual 
rise, and progress, of thunder-storms ; almost all of which 
rise in the north-west, and are originated by a wind, blow- 
ing from that quarter, and continuing to blow, from one to 
four days, like those of the winter. . 
In the summer of 1809 a thunder-storm passed over 
New-Haven from the north-west with great rapidity. It 
continued, as I judged, from an hour to an hour and a half. 
But, although the clouds moved rapidly to the south-east, 
a south-west wind blew the whole of that day ; and, while 
the thunder-storm was over head, blew with great violence. 
This plainly would not have been possible, had not the 
stream of air, which moved these clouds, proceeded 
through the atmosphere at some distance from the earth.* 
On Wednesday evening, Oct. 15th 1799, Mr. Day, Pro- 
fessor of Mathematics and Natural Philosophy in Yale Col- 
lege, and myself being on our return froma journey of | 
several weeks up the Mohawk, and the Hudson, lodged at 
Pittsfield. The weather, during the whole of our journey, 
as well as before, had been extremely mild; except that a 
very light frost, on the evening of the fourth, had changed 
in a small degree the annual foliage through a tract along 
the Mohawk of about fifteen miles. Throughout the day, 
on which we arrived at Pittsfield, a strong and warm south- 
west wind had blown unceasingly. At nine o’clock in the 
evening a furious blast came from the north-west ; and in 
an instant changed the temperature of the air to a severe 
cold. A violent rain, accompanied by thunder and light- 
ning, fell for an hour. At ten, the rain ceased; and we 
went out, to examine the face of the heavens. The clouds 
had become broken: and we discerned with perfect dis- 
tinctness the inferiour stratum, moving rapidly from the 
north-west ; a second, immediately above it, moving from 
*T saw the same facts again repeated in the summer of 1810. 
