18 CLIMATE AND RESOUECES OF 



suited to the cultivation of the vine, because they advance 

 the ripening of the grape more rapidly than chalky and 

 clayey earths, which cool quickly. Hence we see that in 

 examining the calorific effects of clearing forests, it is im- 

 portant to take into account the properties of the soil laid 

 bare." Becquerel, " Des Climats et des Sols boises," p. 137. 



In India the heating of loose sandy soil in the day and its 

 cooling during the night, can hardly have escaped the notice 

 of any one who has walked over it. Its coolness in the morn- 

 ing compared with that of the neighbouring fields of a more 

 clayey character of soil with a hardened surface, is remark- 

 able, and is due to its radiative power, caused by the loosened 

 state of division of its particles. The loose sandy soils are in 

 the morning often wet with dew, when there is no dew on the 

 hardened surface of the fields close by, showing that the 

 surface temperature of the former has been reduced below 

 dew-point, while it has not been reduced to that extent on 

 the latter soils. 



Were the soil of the fields with the hardened surface broken 

 up and pulverized, it being of a more clayey nature, a better 

 radiator, and not so retentive of heat, its temperature would 

 be reduced below that of the sandy soil, and it would condense 

 a greater amount of dew on its surface. Again, the power 

 of retaining heat possessed by humus being less than that of 

 purely mineral soils, the greater the amount of humus incor- 

 porated with the soils of our fields, the greater would be their 

 powers of absorbing and radiating heat, and the greater the 

 influence they would exert in reducing the temperature of a 

 hot climate ; a strong reason for burying as much vegetable 

 matter as possible in the soil. 



If we reverse the experiment of the paving- stones and take 

 ordinary earth, and by moistening it and using pressure bring it 

 into a state as nearly as possible resembling stone, we shall find 



