54 CLIMATE AND EESOURCES OF 



periods of dry weather) can ill afford to lose. The average 

 loss of water by surface- drainage throughout the country is 

 probably half the rainfall, but supposing it to be ten inches, 

 then the loss per acre would be one thousand tons or 640,000 

 tons per square mile, which increases the floods. 



There are many thousands of square miles of country 

 within the drainage basin of the Ganges that could be made 

 safe against famine and the effects of droughts by taking care 

 of the rainfall ; and at the same time the climate of Upper 

 India would be improved, and floods and their ill effects would 

 be no more known throughout the lower lands and in Bengal. 

 One of the ill effects of floods in Bengal is, that the banks 

 which are made round the rice -fields to retain the rainfall, are 

 broken by the rush of the flood-water, and are thus rendered 

 unable to retain sufficient either of the flood-water, or the 

 rain which falls on the land, for the wants of the rice crop.* 



From the foregoing pages it will be seen that it is during 

 the hot weather, when the capacity of the atmosphere for 

 holding the vapour of water in suspension is at its maximum, 

 and when the air would be most cooled by evaporation from 

 the surface of the earth, solar heat being expended in evapo- 

 ration, that the minimum amount of moist evaporative surface 

 is presented to the influence of the rays of the sun. There is 

 next to no vapour in the atmosphere to moderate the force 

 of the direct rays of solar heat falling on the surface of the 

 earth, which being exposed to their unmitigated heat becomes 

 excessively heated, and heats the air coming in contact with 

 it. Any method by which we can increase the evaporative 

 surface of the country, and diminish the extent of its bare 

 reflective surface, will tend to diminish the heat of its climate. 

 Trees and vegetation of any kind will do this, in so far as 

 they shade the ground from the direct rays of the sun, and 

 * See Appendix C, p. 102. 



