1other, and are joined with five rundles; these rundles
are two and a half
digits thick and are placed three digits apart. Thus a drum is made, which
is a palm 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
palm above this little axle is a second small square iron axle, the thickness of
which is three digits; this one, like 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 hollowed-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 little 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 pulley set between the beams of the crane-arm.
digits thick and are placed three digits apart. Thus a drum is made, which
is a palm 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
palm above this little axle is a second small square iron axle, the thickness of
which is three digits; this one, like 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 hollowed-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 little 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 pulley 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 oblique 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.
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 oblique 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.