PUMPING WATERS. 83 



adapted to electric driving, and a special arrangement 

 of a bye-pass between suction and delivery pipes 

 takes the place of a clutch. These pumps are also 

 fitted with Merryweather's patent variable stroke 

 mechanism, by means of which the quantity of water 

 delivered and the pressure can be controlled, while 

 the pump shaft is being driven at a constant speed. 

 Pumps fitted with tjjis arrangement offer many 

 advantages where a pump is required for domestic 



FIG. 73- 



FIG. 74. 



water supply and fire protective purposes. When 

 running at a short stroke it is capable of forcing 

 water through long lines of piping, and to great 

 heights, for filling tanks, reservoirs, etc., and in the 

 event of an outbreak of fire the pump can be run up 

 to its full capacity, and large quantities of water 

 thrown with great force on to the fire. 



The variation in stroke is effected by means of a 

 sliding eccentric, provided with internal gearing for 

 adjusting the eccentric relative to the crank shaft, 



