Caleb Atwater on the Wmds of the West. 281 



within my reach might be multiplied to a much greater ex- 

 tent, but they are probably unnecessary. 



But another current of air prevails here, especially in the 

 cold months, coming from the mouth of the Missouri, which is 

 a little to the south of west of this place. This current is 

 colder than the preceding one, and though moist, yet not as 

 much so as the one already described. It prevails generally 

 in October and November, before our warm weather is over, 

 and produces frosts and a chilly dampness, and what I have 

 observed nowhere else, especially on the east side of the 

 AUeghanies, it produces a kind of faintness at the breast. 



People of delicate habits, coming here from the northern 

 and eastern states, uniformly complain of this faintness. It is 

 not perhaps extraordinary that this current of air should be 

 cold, proceeding as it does from a high northern latitude, 

 along the great chain of rocky mountains in the northwest ; 

 that it should be moist, and perhaps also that it should affect 

 the animal economy unpleasantly, may possibly be attributed to 

 its passing such a length of way over the waters of the 

 Missouri, and the wet prairies and barrens lying so exten- 

 sively between us and the head waters of that stream. The 

 luxuriant vegetation which covers these prairies and barrens 

 at that season of the year, begins to putrefy, and fills with un- 

 healthy exhalations every gale of wind which passes over 

 them. 



At the mouth of this river (Missouri,) which is in about lati- 

 tude 38° north, this current of air is extremely cold in the 

 winter months. It diverges from this point, and produces ex- 

 treme cold at a considerable distance to the south of it on the 

 Mississippi river. General Rector, the present surveyor ge- 

 neral of the United States, who keeps his office at St. Louis, 

 informs, that he has known the Mississippi at St. Genevieve, 

 in latitude about 37"*, so firmly covered with ice in one night, 

 as to be able to bear horses and cattle the ensuing day. This 

 circumstance must have been owing to the sudden change of 

 the current of air from south to the northwest, descending 

 the Missouri river from the cold regions at its sources* 



