298 



[October, 1912. 



the soil, but in the immediate future I can hold out no hope of doing any- 

 thing to assist the majority of the ryots who are lifting water from wells. 

 Engine-driven Piston Pumps. 



We are endeavouring to introduce mechanical methods of lifting 

 water in place of those which involve the necessity for employing cattle. 

 For a long time I have been trying to introduce mechanical working 

 on a smaller scale than is economically possible with centrifugal pumps, 

 and this year I have induced Messrs. Massey & Co., of Madras, to exhibit 

 the results of our joint labours. It consists of a 3j H. P. oil engine driving 

 through suitable gearing a pair of loose piston pumps. Each pump is 

 6 in. in diameter, and the pair are capable of lifting about 6,500 gallons 

 of water per hour from a depth of 40 ft. The pump is the largest of this 

 type we propose to make, as it is not intended to supersede centri- 

 fugal pumps when the quantity of water available justifies their 

 employment. They are 5 in. in diameter and are driven by a 2 

 H. P. engine and on a lift of 29J ft. They discharge 4,140 gallons of water 

 per hour. Recently I tested a pair of 4 in. pumps which were working 

 on a lift of 33 ft. and discharged 1,900 gallons per hour. It can be worked 

 on a well of considerable depth, and can deal with comparatively small 

 quantities of water in a fairly efficient way. It is necessary that these 

 pumps should be placed above the higher water level, and the level of the 

 water in the well must not be more than about 25 ft. below the level 

 of the pump, as the pump cannot suck water from a greater depth. 

 If therefore the water level fluctuates more than 25 ft. either the pump 

 must be shifted to a higher level during the rainy season or it must be 

 fitted up in a water-tight chamber. Either alternative is unsatisfactory, 

 but the difficulties can be got over completely by using drowned centri. 

 fugal pumps, which are placed at the bottom of the well ; the runner 

 revolves in a horizontal plane and is driven by a vertical shaft which can 

 be carried to the top of the well. The objection to this type of pump 

 is mainly the expense, but it also requires more careful supervision in 

 the running than does the ordinary type of pump which we 

 now employ. The double piston pumps are entirely free from these dis- 

 advantages, and in a deep well it is only necessary to use a longer 

 piston to obtain the same degree of efficiency in workiug as 

 when the lift is small. A pair cf cattle workng a mhote cannot 

 be expected to work on an average more than six hours a day, but 

 a double piston pump may be run the whole day through, and a pair of 5 

 in. pumps may be considered equivalent to four mhotes, whilst a pair of 

 6 in. pumps will easily do as much work as six mhotes. The cost of 

 lifting water by these pumps works out roughly at about one-half the 

 cost when cattle power is employed. 



Comparative Statistics- 



With oil engines and centrifugal pumps the cost of lifting water 

 decreases per unit as the quantity to be lifted increases, so that the 

 larger the supply of water the greater is the saving in substituting 

 mechanical methods for those which have hitherto been used. Where 

 the water-supply is large, this is already tolerably well recognised by 

 the ryots, and there is no necessity to refer to it here. The advantages 

 of very small installations, however, are not so apparent, and it seems 

 desirable to show how matters really stand. Let us assume that we have 

 a well which will yield 50,000 gallons of water pei day and that the 

 vertical lift is 30 ft. This involves doing useful work to the extent of 

 5,000,000 foot pounds a day. and the cost of lifting water by cattle will 



