BOOK VI. 



A BARREL. 



B STRAIGHT LEVERS. C USUAL CRANK. 



E RlM OF THE SAME WHEEL. 



SPOKES OF WHEEL. 



which is turned by water power, for it lacks the buckets of a water-wheel 

 and it lacks the nave of a carriage wheel. In the place of the nave it has a thick 

 barrel, in which are mortised the lower ends of the spokes, just as their upper 

 ends are mortised into the rim. When three windlass men turn this machine, 

 four straight levers are fixed to the one end of the barrel, and to the 

 other the crank which is usual in mines, and which is composed of two limbs, 

 of which the rounded horizontal one is grasped by the hands ; the rect- 

 angular limb, which is at right angles to the horizontal one, has mortised in its 

 lower end the round handle, and in the upper end the end of the barrel. This 

 crank is worked by one man, the levers by two men, of whom one pulls while 

 the other pushes ; all windlass workers, whatsoever kind of a machine they 

 may turn, are necessarily robust that they can sustain such great toil. 



The third kind of machine is less fatiguing for the workman, while it 

 raises larger loads ; even though it is slower, like all other machines which 

 have drums, yet it reaches greater depths, even to a depth of 180 feet. It 

 consists of an upright axle with iron journals at its extremities, which 

 turn in two iron sockets, the lower of which is fixed in a block set in the 

 ground and the upper one in the roof beam. This axle has at its lower end a 



