234 BEXJ. PIKE'S, JTI., DESCRIPTIVE CATALOGUE. 



Fig. 253. 





Forcing Pump. (Fig. 253, as above.) A pump which 

 is capable of driving a stream of water above the pump 

 barrel by means of compressed air, and illustrates the action 

 of the fire engine. It consists of a glass cylinder, D, with 

 solid piston, G, connected by a rod to a handle, E ; at the 

 bottom of the cylinder there is a valve, H, opening upwards, 

 having a pipe for communicating with the water, a strong 

 glass air vessel, K, at the top of which is a cap and jet, the 

 lower part, i, extending nearly to the bottom of the air 

 vessel, where there is a valve, P, opening upwards, and a 

 bent tube, M, connecting the air vessel with the cylinder of 

 the pump ; the jet is sometimes made so that it may be 

 turned in any direction. To use, the pump-handle and piston 

 are drawn up ; a vacuum being produced below the piston, 

 the pressure of the atmosphere on the water of the well 



