12 CLIMATE AND RESOUECES OF 



combined. But where there is heat without moisture, or 

 rather with a minimum amount of moisture, as in the Sahara 

 and other deserts, no vegetation, or next to none, exists, or 

 can exist. The dry heat of these deserts, and of Upper India 

 during the hot season, very much exceeds that of any country 

 where there is a great amount of vegetation. Of two countries 

 lying under the same degree of latitude, the one well covered 

 with forests and vegetation, and the other devoid of vegeta- 

 tion, the summer heat of the latter will greatly exceed that of 

 the former. The heat of the plain of the Amazon river a 

 country covered with forests is said to be sometimes as high 

 as 106 Fahrenheit in the shade, on the equator, for two 

 hours in the day, from 2 till 4 P.M., when the sun is near the 

 line. This is considered the greatest heat known in a forest- 

 covered country, with consequently a damp climate ; and 

 here, also, is the richest, or rather rankest vegetable growth 

 in the world, the result of great heat and moisture com- 

 bined. 



Other conditions being equal, a difference of * 9 of a degree 

 of heat, Fahrenheit, is considered the allowance that should 

 be made between any two places for every degree of latitude 

 difference there may be in their geographical positions, in 

 computing their mean temperature. Then, as Upper India lies 

 between the parallels of 25 and 33 N., its mean temperature, 

 according to its geographical position, should be from 22 '5 

 to 29'7 Fahrenheit lower than places on the equator; instead 

 of which, if we examine a climatological chart, giving the 

 isothermal lines, we find the line of greatest mean heat runs 

 through Upper India ; and only in Upper India and in Africa 

 does the line run to the north of the tropic of Cancer. 



In Africa the cause is the Sahara. In Upper India the 

 whole country, during April, May, and June, is virtually a 

 desert ; and it is the great heat generated by it during these 



