Proximate Causes of certain Winds and Storms. 289 



neighborhood of the mountains, where westerly winds are found to 

 have a greater predominance than in the regions farther east.* 



This then is a particular, in which the eastern side of N. America, 

 differs widely from the western coast of both America and Europe, and 

 the person who has witnessed the change of temperature, produced by 

 our N. West winds, in a single night, or read of the effects of certain 

 winds in other countries, of the Sirocco for instance, in Italy, will not 

 be disposed to deny, that it is fully adequate to the production of the 

 low medium temperature of North America. The vast elevated pla- 

 teaus, and enormous ridges of Central Asia, stand in the same rela- 

 tion to China, that the Rocky Mountains do to the United States. 

 It is slated that the greatest cold experienced at Pekin, occurred dur- 

 ing the prevalence of a wind from the north-west. In Japan " in win- 

 ter the north and north-west winds are exceedingly sharp, and bring 

 along with them an intense frost." Make Brun. It is to be particular- 

 ly remarked, that the peculiarities of our climate, cease in latitude 

 30°, where the westerly winds are limited on the south. St. Augustine 

 and Grand Cairo have very nearly the same mean temperature. 



The great vicissitudes of our climate, are due to a cause nearly re- 

 lated to that which has just been assigned for its low mean tempera- 

 ture — to the fact, that our predominant winds are from the west, and 

 therefore trade winds. Any country whose predominant winds come 

 from over the land, will be subject to great vicissitudes of tempera- 

 ture. China and the United States agree in this particular. 



The account commonly given of the origin of the land and sea 

 breezes, may serve for illustration. The land, it is said, is more in- 

 tensely heated than the water by the sun during the day, and the sea 

 breeze prevails ; it radiates more during the night, and the movement 

 is in the contrary direction. Now suppose two places to be so situa- 

 ted, as to be subject to a constant breeze but the one to a breeze 

 reaching it after traversing an extensive tract of land, the other from 

 over an equal expanse of water. There can be no doubt that the 

 latter would enjoy the most uniform temperature. The place where 

 the land breeze prevailed, would be hotter in the day and colder at 

 night. But what is here supposed and stated, respecting places of 

 limited extent, such as a city or county, and different hours of the 



*See Lewis and Clarke's register of tlie winds during the winter of 1804-5, and 

 Franklin's Narrative. 



