BOOK VI. 



179 



A — Posts. B — Axle. C — Wooden bars. D — Piston rod. E — Short piece of wood. 

 F — Drain. G— This man is diverting the water which is flowing out of the drain, 



TO PREVENT IT FROM FLOWING INTO THE TRENCHES WHICH ARE BEING DUG. 



own weight, the piston is pushed in. In this way, the water which the pipe 

 contains is drawn through the openings in the disc and emptied by the piston 

 through the spout into the drain. There are some who place a hand-bar 

 underneath in place of the short piece of wood. This pump, as also the last 

 before described, is less generally used among miners than the others. 



The fourth kind is not a simple pump but a duplex one. It is made as 

 follows. A rectangular block of beechwood, five feet long, two and a half 

 feet wide, and one and a half feet thick, is cut in two and hollowed out wide 

 and deep enough so that an iron axle with cranks can revolve in it. The axle 

 is placed between the two halves of this box, and the first part of the axle, 

 which is in contact with the wood, is round and the straight end forms a 

 journal. Then the axle is bent down the depth of a foot and again bent so 

 as to continue straight, and at this point a round piston-rod hangs from it ; 

 next it is bent up as far as it was bent down ; then it continues a httle way 

 straight again, and then it is bent up a foot and again continues straight, 

 at which point a second round piston-rod is hung from it ; afterward it 



