TRANSACTIONS OF SECTION G. 



749 



II. The Application of the Puinping Poiver. — The motive power consists of a 

 230 horse-power compound surface-condensing engine, employed to pump from 

 the bore-holes into a masonry tank by the engine foundations, from which tank the 

 water is forced by the same engine to a reservoir at an elevation of 260 feet. The 

 engine is made to work the force-pump by means of a tail rod from the low-pressure 

 cylinder, the bore-hole pumps being worked by means of rocking levers actuated 

 by a connecting-rod from the crosshead of the engine. There is no flywheel or 

 rotary motion, but a very simple expedient is resorted to to enable the engine to 

 work expansively. This steam distribution is effected by giving a peculiar bell 

 crank form to the levers which convey motion to the well pumps. The etlect of 

 this mode of coupling the pump piston or plunger to the engine piston is to make 

 the pump-resistance diagram so nearly approach the shape of the combined engine 

 diagram that the weight of the moving parts of the engine is of itself, by its 

 inertia, sufficient to equate the two diagrams. 



Steam Distribution. — The engine is of the receiver type, having separate 

 expansion valves on both high- and low-pressure cylinders, adjustable by hand 

 whilst the engine is in motion. 



A careful trial of the engine has been made, and as it is provided with a surface- 

 condenser, it was quite easy to ascertain the exact quantity of steam used by the 

 engine by measuring the air-pump discharge, and adding that discharged from the 

 steam-jackets. 



The efficiencies are as follow: — 



1. Engine efficiency: the proportion which the area of the actual indicator- 

 diagrams bears to the area of the theoretical diagram for the steam admitted to the 

 engine = '644. 



2. Mechanical efficiency, or the portion of the indicated power utilised by the 

 pumps = 87 per cent. 



3. Thermal efficiency, or the portion of the energy due to the fall in temperature 

 of the steam which has been utilised by the engine = •433. 



Units of work per unit of heat = 110 8. 



The steam-cylinders are both steam-jacketed completely — bodies and ends — 

 with steam at boiler pressure. 



The following summary gives the general particulars and cost of the in- 

 stallation : — - 



Steam pressure .... 

 Diameters of cylinders . 



Length of stroke . 

 Diameter of force-pump 



Height of lift .... 



Length of stroke 

 Diameter of bore-hole pumps 



Height of lift .... 



Length of stroke 

 Number of strokes per minute 

 Depth of bore-holes 

 Diameter of bore-holes . 

 Tube surface of condenser . 



,, „ feed heater 



Water pumped in 24 hours . 

 Duty of engine on an evaporation of 10 lb, 



per 1 lb. coal .... 

 Lbs. of steam per I.H.P. per hour 

 „ P.H.P. „ . 

 Indicated horse-power . 

 Pump horse-power 

 Mechanical efficiency . 

 Cost of engine and pumps 

 Total cost of engine, pumps, bore-holes, and 



buildings 



30 ia 



water 



70 lb. per sq. inch. 

 32 in. and 60 in. 

 6 ft. 3 in. 

 18i in. 

 260 ft. 

 6 ft. 3 in. 

 18^ in. 

 100 ft. 

 6 ft. 6 in. 

 12^ 



400 and 500 ft. 

 for 200 ft., and then 18 in. 

 420 sq. ft. 

 140 sq. ft. 

 2i million gallons. 



124 millions. 



15-6 



18-0 



230 



200 



87 per cent. 



6,000/. =30^ per P.H.P. 



9,700/. = 48J/. per P.H.P. 



