Caleb Atwater on the Winds of the West, Til 



tending on the several courts, in all seasons and in all the 

 changes of weather. 



The prevailing currents of air, one of which genepally ob- 

 tains in Ohio, are three* 



The first comes from the Mexican Gulf^ ascending the 

 Mississippi and its larger tributary branches quite to their 

 very sources^ 



The second proceeds from the back of mountains to th-e 

 west, descends the Missouri to its mouth, and then spreads 

 over a vast extent of country. 



The third comes down the great northern and north- 

 western lakes to the south end of Lake Michigan and the 

 southern shore of Lake Erie, where it spreads over the region 

 «f country lying to the south of them. 



That current of air which comes from the Mexican Gulf, 

 is warmer, and perhaps more moist, than any other which pre- 

 vails here. After a iew 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 go to the southward a considerable distance. 

 Other causes 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 of 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 

 Aberdeen, which is opposite to Marysville in Kentucky, at least 

 two-thirds of the distance which that river washes the southern 

 shore of this state. The reason is obvious, because there ar» 

 ao falls in a sandstone formation 



