262 SCIENCE PROGRESS 



ignition current. The pump can therefore be started and stopped 

 from a switchboard. 



A pump of the type just described was tested by Prof. 

 W. C. Unwin, F.R.S., M.I.C.E., in September 1909; using a 

 pump of only 16 h.p. delivering 1,621 gallons per minute to a 

 height of 32'87 ft. and making 13-8 complete cycles per minute, 

 the fuel consumption was ro63 lb. of anthracite per water- 

 horse-power-hour. 



In the official report that was issued, Prof. Unwin states 

 that "the fuel consumption in these trials, reckoning on the 

 work done in lifting water, was less than any other ' pumping 

 arrangement,' either by gas or steam, hitherto recorded." 



Prof. Unwin adds that " the pump works absolutely 

 automatically, without attention when once adjusted and starts 

 with a charge of compressed air with the greatest ease and cer- 

 tainty. Starting all cold, an explosion occurred in five seconds 

 and the pump continued working regularly. In these trials 

 the ignition was effected by a small motor-car battery and 

 small ' Reliance ' motor-car igniting plug. The pump worked 

 throughout the trials with varying lift without any change in 

 the gas and air mixture or any alteration in the cushion volume. 

 Also without a single misfire or hitch of any description." 



Later tests carried out on a pump of twice the size of that 

 tested by Prof. Unwin have afforded the following results : 



Gallons of water raised per minute 3>!50 



Actual lift of water 35*6 ft. 



Horse-power in water lifted 34 



Cycles per minute I2'2 



Cubic feet of 150 B. Th. U. gas per horse-power-hour . 73 



B. Th. U. per water-horse-power-hour 10,950 



Thermal efficiency (on water lifted) 23" 1 per cent. 



Equivalent anthracite coal per water-horse-power-hour . 0*95 lb. 



Before leaving this type of pump it is interesting to note that 

 the Metropolitan Water Board, as the result of a most thorough 

 investigation by a special committee, have decided to adopt 

 Humphrey pumps for their pumping installation at Chingford. 

 The quantity of water to be pumped is 180,000,000 gallons per 

 twenty-four hours and the lift 25 to 30 ft. For this duty there 

 will be erected five Humphrey pumps, four of which will each 

 have a capacity of 40,000,000 and one of 20,000,000 gallons per 

 day; thus each of the larger units will have an output equivalent 



