UPPER INDIA. 23 



The daily work of the sun, in the case of a country with a 

 hardened reflecting surface-soil, is confined to raising the 

 temperature of an already warm surface. No depth of soil is 

 heated, the whole energy of the sun's heat is expended on the 

 surface skin-deep. 



On the other hand, when the soil is deeply broken up and 

 well pulverized the mass of soil so broken up loses at night, 

 by radiation to the depth it has been broken up and pulverized, 

 the heat it acquired by absorption the previous day, the rays 

 of the sun fall in the morning on a surface chilled by radiation, 

 and probably wet with dew, below which is a mass of soil 

 also chilled by radiation. The daily work of the sun, in this 

 case, is first to convert the dew deposited on the surface (should 

 dew have formed) into vapour, and afterwards to raise the 

 temperature of the mass of the soil as deeply as it was 

 pulverized and has been chilled by radiation. 



A large amount of the heat of the sun will be expended in 

 converting the dew into vapour, and a further amount in 

 raising and keeping up the temperature of the mass of 

 loosened soil. The amount of heat that will make a reflective 

 surface unbearably hot will have but a slight effect in raising 

 the temperature of an absorbent surface, particularly when 

 backed up by absorbent substances; and here we have an 

 absorbent surface backed up by a mass of absorbent soil. 

 The heat of the climate of a country being obtained from and 

 dependent on the heat of the surface of the country, the more 

 we reduce the heat of the surface the more must the climate 

 of a country be reduced in temperature. 



The following experiments show the difference between the 

 absorbent powers of a pulverized soil and one left hard and 

 compact. 



On the 12th April, 1871, I found, at four P.M., in a field 

 which had been twice irrigated for the cold-weather crop, that 



