BOOK VI. 



187 



for there hangs no pump-rod from the iron key of these claws, for it can be of 

 no use in the last pump. In turn, when the first pump-rod descends, each 

 set of " claws " is lowered, each pump-rod and each piston-rod. And by this 

 system, at the same time the water is lifted into the tanks and drained out of 

 them ; from the sump at the bottom of the shaft it is drained out, and it 

 is poured into the trough of the tunnel. Further, around the main axle there 

 may be placed two water wheels, if the river supplies enough water to turn 

 them, and from the back part of each round iron crank, one or two pump-rods 

 can be hung, each of which can move the piston-rods of three pumps. 

 Lastly, it is necessary that the shafts from which the water is pumped out in 

 pipes should be vertical, for as in the case of the hauling machines, all pumps 

 which have pipes do not draw the water so high if the pipes are inclined in 

 inclined shafts, as if they are placed vertically in vertical shafts. 



If the river does not supply enough water-power to turn the last- 

 described pump, which happens because of the nature of the locality 

 or occurs during the summer season when there are daily droughts, a 

 machine is built with a wheel so low and light that the water of ever so little a 



A — Water wheel of upper machine. B — Its pump. C — Its trough. D- Wheel of 



LOWER MACHINE. E ITS PUMP. F — RACE. 



