BOOK VI. i8i 



is !)ent down the same distance as it was bent up the last time ; the other 

 end of it, which also acts as a journal, is straight. This part which protrudes 

 through the wood is protected by two iron washers in the shape of discs, to 

 which arc fastened two leather washers of the same shape and size, in order 

 lo prevent the water which is drawn into the box from gushing out. These 

 discs are around the axle ; one of them is inside the box and the other 

 outside. Beyond this, the end of the axle is square and has two eyes, in 

 which are fixed two iron rods, and to their ends arc weighted lumps of lead, 

 so that the axle may have a greater propensity to revolve ; this axle can 

 easily be turned when its end has been mortised in a crank. The upper part 

 of the box is the shallower one, and the lower part the deeper ; the upper 

 part is bored out once straight down through the middle, the diameter of the 

 opening being the same as the outside diameter of the column pipe ; the 

 lower box has, side by side, two apertures also bored straight down ; 

 these are for two pipes, the space of whose openings therefore is twice as 

 great as that of the upper part ; this lower part of the box is placed 

 upon the two pipes, which are fitted into it at their upper ends, and the 

 lower ends of these pipes penetrate into trunks which stand in the 

 sump. These trunks have perforations through which the water flows into 

 them. The iron axle is placed in the inside of the box, then the two iron 

 piston-rods which hang from it are let down through the two pipes to the depth 

 of a foot. Each piston has a screw at its lower end which holds a thick iron 

 plate, shaped like a disc and full of openings, covered with a leather, and 

 similarly to the other pump it has a round valve in a little box. Then the 

 upper part of the box is placed upon the lower one and properly fitted to it on 

 every side, and where they join they are bound by wide thick iron plates, and 

 held with small wide iron wedges, which are driven in and are fastened with 

 clamps. The first length of column pipe is fixed into the upper part of the 

 box, and another length of pipe extends it, and a third again extends this one, 

 and so on, another extending on another, until the uppermost one reaches the 

 drain of the tunnel. When the crank worker turns the axle, the pistons in 

 turn draw the water through their discs ; since this is done quickly, and 

 since the area of openings of the two pipes over which the box is set, is twice 

 as large as the opening of the column pipe which rises from the box, and since 

 the pistons do not hft the water far up, the impetus of the water from the 

 lower pipes forces it to rise and flow out of the column pipe into the drain of 

 the tunnel. Since a wooden box frequently cracks open, it is better to 

 make it of lead or copper or brass. 



The fifth kind of pump is still less simple, for it is composed of two or 

 three pumps whose pistons are raised by a machine turned by men, for each 

 piston-rod has a tappet which is raised, each in succession, by two cams on 

 a barrel ; two or four strong men turn it. When the pistons descend into 

 the pipes their discs draw the water ; when they are raised these force the 

 water out through the pipes. The upper part of each of these piston-rods, 

 which is half a foot square, is held in a slot in a cross-beam ; the lower part, 

 which drops down into the pipes, is made of another piece of wood and is 

 round. Each of these three pumps is composed of two lengths of pipe fixed 



