Proximate Causes of certain Winds and Storms. 287 



The low mean temperature of the eastern coasts of Asia and N. 

 America remains therefore unaccounted for. Prest. Dwight's argu- 

 ment respecting our north-west winds, by which he proves that they 

 descend from the higher regions of the atmosphere, although ingen- 

 ious and able, does not reach the exigencies of the case, because the 

 question still arises, "Why is not Europe infested with the same winds, 

 or with winds from some other quarter, having similar characters?" 

 The central fire of some philosophers occurs to the mind as the prob- 

 able cause of the difference, and the idea is suggested that the walls 

 of the great interior furnace are thicker on the eastern shores of Asia 

 and America than elsewhere. But it seems unphilosophical to as- 

 sign for a known effect a cause, whose existence even is regarded 

 by many as problematical, and which we can never prove to operate 

 in the manner we suppose. 



The Rocky Mountains appear to constitute the boundary by which 

 the cold is separated from the mild and temperate part of North 

 America. " I am confident (says Capt. Lewis) that the climate here 

 (at the mouth of the Columbia,) is much warmer than in the same 

 parallel of latitude on the Atlantic ocean, though how many degrees 

 it is now out of my power to determine." The amelioration of the 

 climate seems to be very sensibly felt as soon as the great ridge is 

 passed. "It was impossible to avoid remarking the great superior- 

 ity of climate on the western side of that lofty range. From the in- 

 stant the descent towards the Pacific commences, there is a visible 

 improvement in the growth of timber, and the variety of forest trees 

 greatly increases."* 



Our attention is therefore drawn to these mountains, as probably 

 in some way the cause of the diversity of temperature that is ob- 

 served on their opposite sides, and the following may be the true rea- 

 son of the low mean temperature of the eastern part of North Amer- 

 ica. 



The Rocky Mountains, stretch from the table land of Mexico, in- 

 to the immediate vicinity of the polar sea. Throughout their whole 

 extent, they nowhere descend much below the region of perpetual 

 congelation, and in many places they ascend far into it. 



(a.) Some gentlemen attached to Major Long's expedition, as- 

 cended James' Peak, lat. 39° 23', and give the following account 



• jDrummond, in Franklin's IVarrative, p. 256. 



