698 INFLUENCE OF CLIMATE 



If we pass to the warm and temperate latitudes 

 of Europe, where the growth of vegetation conti- 

 nues from six to ten months in the year, and the 

 inhabitants are seldom pinched with extreme 

 cold, or exhausted by excessive heat, the popu- 

 lation is about 170,000,000, on a territory of 

 1,425,000 square miles. In the United States, 

 the climate and soil of which are equally genial 

 and fruitful, there is a territory of 2,300,000 square 

 miles, with a population of 17,000,000; which, 

 should it go on doubling every thirty-six years, 

 will be 150,000,000 in another century. And if 

 the period of doubling be then fifty years, it will 

 be 600,000,000 in another century.* Nor can 

 there be a reasonable doubt, that improvements 

 in science, agriculture, the arts, and the adoption 

 of a chiefly vegetable diet, will afford the means 

 of supporting in comfort a much greater popula- 

 tion to the square mile, than has ever yet existed 



* But if a lofty chain of mountains extended north westward 

 across the continent from lat. 24 to 45, like the Himalayas in 

 Asia, it is evident that the middle and northern states would 

 have a climate resembling that of ancient Scythia ; and that their 

 future history would be proportionally modified. As the sovereign 

 of the earth, man has the power of removing forests, draining 

 marshes, dyking rivers, and of improving his condition in an end- 

 less variety of ways. But he cannot alter the mean tempera- 

 ture of the earth, nor any considerable portion of it, the thousandth 

 part of a degree, any more than he can prevent the elevation of 

 mountains, the direction of winds, or the revolutions of planets. 

 In the city of London, with its 400,000 fires, the mean of the 

 year is but 2 higher than in the surrounding country. 



