WATER 551 



A tube or Abyssinian well for shallow water in the tropics is often 

 a temporary necessity. The water is usually within 25 feet of the 

 surface. This tube-well cannot penetrate rock. 



It has the adyantage that the tube, ij- to 4 inches in diameter, may 

 be driyen beneath the upper impervious la\'er and so reach deep water. 

 A pump is attached to the upper length of piping which is embedded 

 in cement at the top. Water is yielded according to the diameter of 

 the pipe, the supply being constant. Thus: — 



ij-inch pipe will yield 150 - 600 gallons of water per hour 



3 )) .) 300 - 1,200 „ 



4 » „ 1,200 - 4,400 „ „ 



The Sulliyan's diamond drill produces a form of bore well that 

 can penetrate rock and produce large supplies of water. The tube 

 can be sunk at an average rate of 28 feet in twenty-four hours. 



Such a bore-hole will produce much more water than a well of 

 6 feet diameter. The Chinese are credited w'ith boring by means of 

 a rope and chisel down to a depth of 1,000 feet in the olden days. 



An ordinary well can be converted into a tube-well by inserting 

 a tube and filling the well with sand and pebbles. 



The pump can be erected some distance away from the well. 



Deep Wells. 



This water supply is derived from a wide catchment area or some- 

 times from distant hills. As a rule the filtration has removed all 

 organic matter but the surface and surroundings of the well must be 

 protected. 



Artesian (from Artois in France) wells are artificial springs. 



The water is pure if it does not contain an excess of mineral 

 matter. A great advantage of this kind is the depth to which they 

 can be sunk, 1,500 to 4,000 feet. In this way cholera can be avoided 

 as at Pondicherry. 



Water can be found in districts formerly considered waterless, 

 by these means as at Queensland, and pure water has been obtained 

 on the sea shore as at Java. 



The water from these wells is sometimes brackish though it is pure 

 and its temperature sometimes raised. 



WATER— TRANSPORT. 



House to house distribution by means of pipes is a rare luxury in 

 the tropics. A supply in each street is not as common as it should 

 be. In India the Mahommedan water-carrier serves each house from 

 his mashak of goat or calf skin by means of which he can generally 

 infect water that is pure prior to its being put into the receptacle. 



35 



