UNITED STATES OF AMERICA. 287 



North-west of the great lakes of Canada, lie vast, uncultivated fro- 

 zen regions. From these blows the north-west, one current of the 

 three great prevailing winds of the United States, more especially in 

 the winter. It is cold, dry and elastic, and not unfrequently violent 

 and tempestuous. Along the Mississippi and Ohio rivers, it is often 

 the harbinger of rain in the winter, and of storms in the summer. 

 The mortar and plaister on walls subjected to its action, are harder 

 and more difficult to demolish than those of any other exposure. In 

 an opposite direction, from the atlantic ocean, blow the east, or ra- 

 ther south-east winds, which frequently contend with those from the 

 north-west for the dominion of the atmosphere ; and these conflicts 

 produce in part, the sudden transitions from cold to heat, and the re- 

 verse already noticed. These winds are light and warm, and pro- 

 duce frequent thaws in winter. In the middle and southern states, 

 they often prove destructive to the fruit trees, by awakening the 

 power of vegetation prematurely, swelling the buds, and opening the 

 flowers, which are always blasted by subsequent frosts. 



Winds directly from the north are scarcely known in the United 

 States; but from the north-east they are frequent, along the atlantic 

 coasts. They are cold, chilly and disagreeable, being saturated with 

 moisture, and attended by thick heavy vapours and benumbing fogs, 

 accumulated in their passage over the ocean. On crossing the Al- 

 legany mountains, the north-east winds change their character, and 

 become dry, light and pleasant. The south winds, which are less hot 

 than those from the south-east, are pleasant and agreeable in the 

 summer. The prevailing winds along the Mississippi and Ohio, are 

 from the south-west, and appear to be a ramification of the trade 

 winds. After passing into the gulf of Mexico, they rise along the 

 coasts of Louisiana and Florida, saturated with the warm vapours of 

 the gulf, and bending towards the north, spread over the country in 

 a north-east direction, and are said to produce a difference of three 

 degrees in the temperature of the western and atlantic states. 



Next to the winds, the rains have the most considerable influence, 

 in determining the character of the climate. Numerous and accu- 

 rate observations, made by intelligent Americans, have ascertained, 

 that one third more of water, at a medium falls in the United States, 

 than in Europe. But it falls in less time, and in much heavier show- 

 ers. The proportion of clear to cloudy weathei", is in favour of Ame- 

 rica. From the rapidity of evaporation, it appears, that the air of the 

 United States is drier and less calm than that of Europe. This pow- 

 erful evaporation is also one cause of the copiousness of the dews. 



In confirmation of the position, that the air is drier than that of 

 Europe, it may be added, that the former is saturated with a greater 

 quantity of the electric fluid than the latter. The frequency of thun- 

 der gusts affords evidence of this : It may also be ascertained by 

 drawing a silk ribbon briskly over a piece of woollen cloth, which 

 will contract with a promptitude never seen in England or France. 



The quantity of snow that falls and the space of time it covers the 

 ground, have some effect upon the climate. Where it falls in au- 

 tumn, before the earth is much frozen, and continues without inter- 

 mission till the hard freezing weather is over, the earth, having been 

 kept warm, feels, as soon as her winter covering is gone, the power 

 of vegetation begin to operate, and is almost instantaneously clothed 

 with verdure. But in countries where the winter is long and cold, 

 and the face of the earth exposed with little or no covering, it be- 



