OBSERVATIONS ON IKKIGATIOX WORKS IX INDIA. 



171 



a great many details about irrigation woiks, much of which is new, 

 I have no doubt, to most of us ; but perhaps I might be allowed, 

 sir, to refer for a moment to the physical conditions which have 

 rendered irrigation in India, as well as in other countries, possible 

 or feasible. 



Xow, you cannot have irrigation without abundance of water 

 from rain. Where does the rainfall of India come from 1 Xo doubt 

 some of those present are perfectly familiar with these matters, with 

 the great physical arrangements which Providence has made for the 

 supply of water to tropical regions AWthout which they would be 

 waste deserts ; and India is a splendid example of the operation of 

 this physical machinery which has been set in motion from the earliest 

 times ; in fact, since the present distribution of land and sea came 

 into existence. The water that falls on the surface of India comes, 

 I need hardly say, from the ocean ; but the question arises, why does 

 it come at particular seasons constituting monsoons 1 That may not 

 be so generally known. In these parts we have a rainfall at all 

 times of the year and we are not sm-prised at it ; — though we have 

 been at the amoimt we have had lately ! But why in the case of 

 India, and in the case of the Abyssinian mountains, does the rain fall 

 at certain seasons of the year ? It comes about in this way. It is 

 a splendid result of the combined action of the power and influence 

 of the Sim's heat and the relative distribution of land and sea. 

 During the spring, when the winter is over, the sun is gradually 

 rising towards a vertical position, and it pours down its rays with 

 irresistible power on the vast area of land exposed to them between 

 the two great arms of the Indian Ocean. 



It is remarkable that the sun's rays pass through the air without 

 imparting to the air additional heat — at least to any appreciable 

 degree — but their effect is to warm the surface of the land, and in this 

 way the air overspreading its siu-face. The effect of this is to cause 

 the heated air to rise and so to draw in the winds from the Indian 

 Ocean heavily charged with, moistiure and moving over the lands to 

 the north-east, and forming great masses of cloud which gather over 

 the Ghauts and along the flanks of the Himalayas. The air 

 becomes oppressive, but relief is found in grand displays of 

 electrical phenomena. The rain falls in torrents accompanied by 

 thunder and lightning, imparting verdiu'e to the parched lands and 

 filling the rivers and pools with much needed supplies of water. 



