24 



Experiments have shown that the amount of aqueous vapours 

 that can be held in air of a temperature of 80 is nearly five times 

 as much as can he retained by air at the freezing point. 



Air at 32° can sustain 2-37 grains per cub. ft. 

 >> 60 ,, ,, 5"87 ,, ,, ,, 

 }> 80 ,, ,, 10-81 ,, „ ,, 



Consequently if the temperature of the aii* falls from 80° to 

 60° there must be a precipitation of five grains per cubic foot of 

 air affected by the change of temperature. 



Classifying the districts of India according to amount of 

 rainfall, they are as follows : — 



INCHES. 



Sind. 



Panjab, Khandeish, 'N. and S. Deccan. 



Upper Ganges, Rajputana, Carnatic N. Circas. 



Central India, Central Provinces. 



Western Bengal. 



W. Himalayas, Lower Gangetic. 



Pegu. 



Assam. 



Bay Islands. 



Malabar. 



Concan E. Himalayas. 



Tenasserim. 



Aracan. 



Prom this it will be seen that the rainfall in India is not so 

 great as it might be imagined, and that the N.Wcst portion of 

 Upper India and the whole of the peninsula' have but a small 

 average fall, if we except the narrow strip of country along the 

 Western coast. On the other hand. Eastern Bengal, Assam, and 

 all down the Burmese coast, possess a rainfall which is really large 

 as compared with a country in the temperate zone ; England for 

 instance, which has a rainfall of 36 inches, fairly uniformly 

 distributed if we except Cumberland which has 189 inches. 



Paet II. 



The efi'ects of rainfall in a tropical country are perhaps more 

 evident in the vegetable kingdom, and in the scenery, than in 

 other directions, and it is evident that as most of the rain falls 

 in seven months of the year the rate of growth is abnormal, and 

 this growth is favored by the tropical heat which, while it assists 

 growth during the rainy season, prevents the complete exhaustion 

 of the plant during the dry season by checking its growth, much 

 as the extreme of the winter in England acts on the vegetation of 

 that country. 



