CLIMATOLOGY. 325 



territory lying between the Carolinas, Virginia, and the St. 

 Lawrence,) were astonished to find themselves exposed to an 

 intensity of winter-cold far exceeding that which prevailed in 

 Italy, France, and Scotland, situated in corresponding paral- 

 lels of latitude. But however much a consideration of these 

 climatic relations may have awakened attention, it was not 

 attended by any practical results, until it could be based on 

 the numerical data of mean annual temperature. If, between 

 58 and 30 north latitude, we compare Nain, on the coast of 

 Labrador, with Gottenborg; Halifax with Bordeaux; New 

 York with Naples ; St. Augustine, in Florida, with Cairo ; we 

 find that, under the same degrees of latitude, the differences of 

 the mean annual temperature between Eastern America and 

 Western Europe, proceeding from north to south, are succes- 

 sively 20-7, 13-9, 6-8, and almost 0. The gradual decrease 

 of the differences in this series extending over 28 of latitude 

 is very striking. Further to the south, under the tropics, the 

 isothermal lines are everywhere parallel to the equator in 

 both hemispheres. We see, from the above examples, that the 

 questions often asked in society, how many degrees America, 

 (without distinguishing between the eastern and western 

 shores,) is colder than Europe? and, how much the mean 

 annual temperature of Canada and the United States is lower 

 than that of corresponding latitudes in Europe? are, when 

 thus generally expressed, devoid of meaning. There is a sepa- 

 rate difference for each parallel of latitude, and without a 

 special comparison of the winter and summer temperatures of 

 the opposite coasts, it will be impossible to arrive at a correct 

 idea of climatic relations, in their influence on agriculture and 

 other industrial pursuits, or on the individual comfort or dis- 

 comfort of mankind in general. 



In enumerating the causes which produce disturbances in 

 the form of the isothermal lines, I would distinguish between 

 those which raise and those which lower the temperature. 

 To the first class belong the proximity of a western coast in 

 the temperate zone, the divided configuration of a continent 

 into peninsulas, with deeply indented bays and inland seas ; 

 the aspect or the position of a portion of the land with refer- 

 ence either to a sea of ice spreading far into the polar circle, 

 or to a mass of continental land of considerable extent, lying 

 in the same meridian, either under the equaroi or, at least. 



