260 



SCIENCE PROGRESS 



of the bend b to the water valve chamber w, the discharge 

 pipe d and thus to the water tower wt; the suction tank st 

 embraces the valve box chamber, as shown, so that there is a 

 free access of water to all the water valves v. These water 

 valves are plain mushroom valves opening inwards and held 

 on their seats by light springs. In the top of the combustion 

 chamber are fitted an inlet valve a and an exhaust valve e. 

 A simple interlocking gear is arranged between these two 

 valves, so that when valve a opens and closes it locks itself shut 

 and releases the valve e ; when valve e opens and closes it 

 locks itself shut and releases valve a. Consequently each time 

 that suction occurs in the chamber these valves open in turn. 



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< V}7//»/> v f/ 7 



Fig. i. 



Imagine a charge of gas and air to be compressed in the 

 top of chamber c and fired by a sparking plug which projects 

 through the top casting. All the valves are shut when explosion 

 occurs, so that the increase in pressure drives the water down- 

 wards in the pump and sets the whole column of water in the 

 discharge pipe in motion. The column of water attains kinetic 

 energy while work is being done upon it by the expanding 

 gases, so that when these gases reach atmospheric pressure the 

 column of water may be moving at, say, six feet per second. 

 The motion of this column of water cannot be suddenly 

 arrested ; hence the pressure in c tends to fall below that of 

 the atmosphere and the exhaust valve e opens and also the 

 water valves v. Water rushes in through the water valves 

 mostly to follow the moving column in pipe d but partly to rise 

 in chamber c in an effort to reach the level inside the chamber 



