478 BOOK X. 



other, and are joined with five run dies ; these rundles are two and a half 

 digits thick and are placed three digits apart. Thus a drum is made, which 

 is a pakn and a digit distant from the upright timber, but further from the 

 crane-post, namely, a palm and three digits. At a height of a foot and a 

 pakn above this little axle is a second small square iron axle, the thickness of 

 which is three digits ; this one, hke the first one, turns in bronze or iron 

 bearings. Around it is a toothed wheel, composed of two discs a foot three 

 palms in diameter, a palm and two digits thick ; on the rim of this there 

 are twenty-three teeth, a palm wide and two digits thick ; they protrude 

 a palm from the wheel and are three digits apart. And around this same 

 axle, at a distance of two palms and as many digits toward the upright 

 timber, is another disc of the same diameter as the wheel and a palm thick ; 

 this turns in a hoUowed-out place in the upright timber. Between this disc 

 and the disc of the toothed wheel another drum is made, having likewise five 

 rundles. There is, in addition to this second axle, at a height of a cubit 

 above it, a small wooden axle, the journals of which are of iron ; the ends 

 are bound round with iron rings so that the journals may remain firmly fixed, 

 and the journals, like the httle iron axles, turn in bronze or iron bearings. 

 This third axle is at a distance of about a cubit from the upper small cross- 

 beam ; it has, near the upright timber, a toothed wheel two and a half feet 

 in diameter, on the rim of which are twenty-seven teeth ; the other part of 

 this axle, near the crane-post, is covered with iron plates, lest it should be worn 

 away by the chain which winds around it. The end link of the chain is fixed 

 in an iron pin driven into the little axle ; this chain passes out of the frame 

 and turns over a little puUey set between the beams of the crane-arm. 



Above the frame, at a height of a foot and a palm, is the crane-arm. This 

 consists of two beams fifteen feet long, three palms wide, and two thick, 

 mortised into the crane-post, and they protrude a cubit from the back of the 

 crane-post and are fastened together. Moreover, they are fastened by means 

 of a wooden pin which penetrates through them and the crane-post ; this 

 pin has at the one end a broad head, and at the other a hole, through which 

 is driven an iron bolt, so that the beams may be tightly bound into the crane- 

 post. The beams of the crane-arm are supported and stayed by means of 

 two obUque beams, six feet and two palms long, and likewise two palms wide 

 and thick ; these are mortised into the crane-post at their lower ends, and 

 their upper ends are mortised into the beams of the crane-arm at a point 

 about four feet from the crane-post, and they are fastened with iron nails. 

 At the back of the upper end of these oblique beams, toward the crane-post, 

 is an iron staple, fastened into the lower sides of the beams of the crane-arm, in 

 order that it may hold them fast and bind them. The outer end of each 

 beam of the crane-arm is set in a rectangular iron plate, and between these 

 are three rectangular iron plates, fixed in such a manner that the beams of the 

 crane-arm can neither move away from, nor toward, each other. The upper 

 sides of these crane-arm beams are covered with iron plates for a length of 

 six feet, so that a trolley can move on it. 



