i64 BOOK VI. 



and its lower end mortised into the sill ; these posts are four feet long, one 

 foot thick, and one foot wide. Thus a circular area is made, the diameter of 

 which is fifty feet ; in the middle of this area a hole is sunk to a depth of ten 

 feet, and rammed down tight, and in order to give it sufficient firmness, it is 

 strengthened with contiguous small timbers, through which pins are driven, 

 for by them the earth around the hole is held so that it cannot fall in. In 

 the bottom of the hole is planted a sill, three or four feet long and a foot and a 

 half thick and wide ; in order that it may remain fixed, it is set into the small 

 timbers ; in the middle of it is a steel socket in which the pivot of the axle turns. 

 In hke manner a timber is mortised into two of the large beams, at the top 

 beneath the clamps ; this has an iron bearing in which the other iron journal of 

 the axle revolves. Every axle used in mining, to speak of them once for all, 

 has two iron journals, rounded off on all sides, one fixed with keys in the centre 

 of each end. That part of this journal which is fixed to the end 

 of the axle is as broad as the end itself and a digit thick ; that which 

 projects beyond the axle is round and a palm thick, or thicker if necessity 

 requires ; the ends of each miner's axle are encircled and bound by an 

 iron band to hold the journal more securely. The axle of this machine, 

 except at the ends, is square, and is forty feet long, a foot and a half thick 

 and wide. Mortised and clamped into the axle above the lower end are the 

 ends of four inclined beams ; their outer ends support two double cross- 

 beams similarly mortised into them ; the inclined beams are eighteen feet 

 long, three palms thick, and five wide. The two cross-beams are fixed to 

 the axle and held together by wooden keys so that they will not separate, 

 and they are twenty-four feet long. Next, there is a drum which is made of 

 three wheels, of which the middle one is seven feet distant from the upper 

 one and from the lower one ; the wheels have four spokes which are 

 supported by the same number of incUned braces, the lower ends of which 

 are joined together round the axle by a clamp ; one end of each spoke is 

 mortised into the axle and the other into the rim. There are rundles all 

 round the wheels, reaching from the rim of the lowest one to the rim of the 

 middle one, and Ukewise from the rim of the middle wheel to the rim of the top 

 one ; around these rundles are wound the drawing-ropes, one between the lowest 

 wheel and the middle one, the other between the middle and top wheels. 

 The whole of this construction is shaped like a cone, and is covered with a 

 shingle roof, with the exception of that square part which faces the shaft. 

 Then cross-beams, mortised at both ends, connect a double row of upright 

 posts ; all of these are eighteen feet long, but the posts are one foot thick 

 and one foot wide, and the cross-beams are three palms thick and wide. 

 There are sixteen posts and eight cross-beams, and upon these cross-beams 

 are laid two timbers a foot wide and three palms thick, hollowed out to a 

 width of half a foot and to a depth of five digits ; the one is laid upon the 

 upper cross-beams and the other upon the lower ; each is long enough to 

 reach nearly from the drum of the whim to the shaft. Near the same drum 

 each timber has a small round wooden roller six digits thick, whose ends are 



