METEOROLOGICAL OBSERVATIONS. 141 
winds had alfo a progrefive motion. Had the different 
winds by which the whirlwinds were formed been of 
equal violence, the whirlwinds would have been ftation- 
ary confifting only of a circular motion; but being of 
unequal violence, the whirlwinds had a progreflive moti- 
on, proceeding in different directions at different places, 
according to the direction of the ftrongeft wind. 
The /ummer preceding this hurricane had been in fome 
refpects different from what is common in this part of the 
country. There had been an uncommon drought for two 
months before, which was no where more fevere than in 
the towns upon the river; and in no fummer for feveral 
years, have we had fo much hot weather. This circum- 
ftance is agreeable to the prefumption of theory; for, if 
whirlwinds and hurricanes are derived from the great ra- 
refaction of fome part of the atmofphere, it might be ex- 
pected that the times in which they would happen, would 
be in the moft calm, or hot weather. 
N° X. 
A Letter from J. Madison, E/quire, to D. Rit- 
TENHOUSE, E/quire. 
William and Mary College, Virginia, November, 1779. 
DEAR SIR, 
GREEABLY to promife, I now tranfmit you a 
feries of obfervations upon our climate. They 
comprehend an entire year, and part of the fucceeding. 
I thought once of fending you only a mean of the obfer- 
vations for each month, but as it was a part of our natu- 
ral hiftory, which has never yet been made public, I have 
therefore fent a copy of the journal. Some fingular cir- 
cumftances 
