igS BOOK VI. 



direction. The axle is square and is thirty-five feet long and two feet thick 

 and wide. Beyond the wheel, at a distance of six feet, the axle has four hubs, 

 one foot wide and thick, each one of which is four feet distant from the next ; 

 to these hubs are fixed by iron nails as many pieces of wood as are necessary 

 to cover the hubs, and, in order that the wood pieces may fit tight, they are 

 broader on the outside and narrower on the inside ; in this way a drum is 

 made, around which is wound a chain to whose ends are hooked leather bags. 

 The reason why a drum of this kind is made, is that the axle may be kept in 

 good condition, because this drum when it becomes worn away by use can 

 be repaired easily. Further along the axle, not far from the end, is another 

 drum one foot broad, projecting two feet on all sides around the axle. And 

 to this, when occasion demands, a brake is applied forcibly and holds back 

 the machine ; this .kind of brake I have explained before. Near the axle, 

 in place of a hopper, there is a floor with a considerable slope, having in 

 front of the shaft a width of fifteen feet and the same at the back ; at each 

 side of it there is a stout post carrying an iron chain which has a large hook. 

 Five men operate this machine ; one lets down the doors which close the 

 reservoir gates, or by drawing down the levers, opens the water-races ; this 

 man, who is the director of this machine, stands in a hanging cage beside the 

 reservoir. When one bag has been drawn out nearly as far as the sloping 

 floor, he closes the water gate in order that the wheel may be stopped ; when 

 the bag has been emptied he opens the other water gate, in order that the 

 other set of buckets may receive the water and drive the wheel in the opposite 

 direction. If he cannot close the water-gate quickly enough, and the water 

 continues to flow, he calls out to his comrade and bids him raise the brake 

 upon the drum and stop the wheel. Two men alternately empty the bags, 

 one standing on that part of the floor which is in front of the shaft, 

 and the other on that part which is at the back. When the bag has been 

 nearly drawn up — of which fact a certain link of the chain gives warning — the 

 man who stands on the one part of the floor, catches a large iron hook in one 

 link of the chain, and pulls out aU the subsequent part of the chain toward 

 the floor, where the bag is emptied by the other man. The object of this 

 hook is to prevent the chain, by its own weight, from pulling down the 

 other empty bag, and thus pulling the whole chain from its axle and 

 dropping it down the shaft. His comrade in the work, seeing that the bag 

 filled with water has been nearly drawn out, calls to the director of the 

 machine and bids him close the water of the tower so that there will be time 

 to empty the bag ; this being emptied, the director of the machine first of 

 all slightly opens the other water-gate of the tower to allow the end of the 

 chain, together with the empty bag, to be started into the shaft again, and 

 then opens entirely the water-gates. When that part of the chain which 

 has been pulled on to the floor has been wound up again, and has been let 

 down over the shaft from the drum, he takes out the large hook which was 

 fastened into a link of the chain. The fifth man stands in a sort of cross-cut 

 beside the sump, that he may not be hurt, if it should happen that a link 



