RESERVOIRS. 227 



of its value is that it may be put to this use while it fills 

 the place of a house or barn pump, or both. It may 

 be worked by hand, or attached to a windmill or steam- 

 engine. It has attachments for pipes or hose at the 

 spout, or these may be made beneath the surface. The 

 sand-strainer (fig. 109) may be attached to this or any 

 other pump. While there are a great variety of pumps 

 that may be turned to the uses of the irrigator, yet these 

 undoubtedly meet all the requirements of those who may 

 be called upon to use them, from the greatest operator to 

 the least. 



RESERVOIRS. A vast amount of irrigation has been 

 done, and may be done, by the help of storage reservoirs, 

 in which the rainfall of a part of the year is impounded 

 for use during the dry season. The most prominent 

 examples of these storage reservoirs are in India, where 

 ancient works exist, which surpass in immensity, and 

 solidity of construction, what are usually considered as the 

 wonders of the world. The people of India, 100 millions 

 of which depend for their existence upon the water sup 

 plied by these reservoirs for the irrigation of their land, 

 have taken advantage of every valley, ravine, or nook, 

 large and small, and have converted them into storage 

 reservoirs, by throwing across them banks of earth, in 

 which the water supply is husbanded, so that none may 

 run to waste. In fourteen districts of the Madras Presi 

 dency alone, no less than 43,000 irrigation reservoirs are 

 recorded by the Indian Government as being in effective 

 operation, while at least 10,000 have fallen into disuse. 

 The average length of the embankments is half a mile ; 

 one of them, now no longer in use, extending for 30 

 miles, and enclosing a space of 80 square miles, or over 

 50,000 acres. The second largest, which is still in use, 

 has an area of 35 square miles, and a dam 12 miles in 

 length. Curious statisticians have calculated that these 

 Indian embankments contain altogether as much earth as 



