Caleb Atwater on the Winds of the West. 277 
attending on the several courts, in all seasons and in all the chang- 
es of weather. : 
The prevailing currents of air, one of which generally ob- 
tains in Ohio, are three. 2 bo 
The first comes from the Mexican Guif, ascending the Mis- 
sissippi and its larger tributary branches quite to their very 
8. ; 
The second proceeds from the back of mountains to the west, 
descends the Missouri to its mouth, and then spreads over a 
vast extent of country. 
The third comes down the great northern and northwes- 
tern lakes to the south end of Lake Michigan and the south- 
em shore of Lake Erie, where it spreads over the region of 
country lying to the south of them. of Ge AE 
That current of air which comes from the Mexican Gulf, 
iswarmer, and perhaps more moist, than any other which pre- 
vails here. After a few days prevalence, it uniformly brings 
rain along with it. That this current of air should be very 
warm may be readily conceived, when we reflect that it comes 
from a hot tropical region; and that it should be very moist 
excites no surprise, when it is considered, that in its passage 
upwards it passes wholly over water, and through the warm 
mists and fogs constantly ascending from the Mississippi and 
its tributaries. This current prevails much more along the 
Ohio river than it does at any considerable distance from it. 
One consequence is, that the climate in the immediate vicinity 
of the Ohio river is warmer, than it is either north or south 
of it, unless you goto the southward a considerable distance, 
Other causas may, and probably do, in a greater or less degree, 
Contribute to produce this result, and I will here state them : 
First, the Ohio runs on a surface less elevated above the - 
sea than the country, either north or south of it, but this dif- 
ference is trifling through the whole of the sandstone forma- 
tion. This formation prevails from the head. of the Ohio to 
n, which is opposite to Marysville in Kentucky, at least 
'wo-thirds of the distance which that river washes the southern 
shore of this state. ‘The reason is obvious, because there are 
no falls in a sandstone formation. 
Lae in 
