ether at the upper end by a bolt, then spread apart at the
bottom, and so set up, being kept upright by ropes attached at the upper
ends and fixed at intervals all round. At the top is fastened a block,
which some call a "rechamus." In the block two sheaves are enclosed,
turning on axles. The traction rope is carried over the sheave at the
top, then let fall and passed round a sheave in a block below. Then it
is brought back to a sheave at the bottom of the upper block, and so it
goes down to the lower block, where it is fastened through a hole in
that block. The other end of the rope is brought back and down between
the legs of the machine.

2. Socket-pieces are nailed to the hinder faces of the squared timbers
at the point where they are spread apart, and the ends of the windlass
are inserted into them so that the axles may turn freely. Close to each
end of the windlass are two holes, so adjusted that handspikes can be
fitted into them. To the bottom of the lower block are fastened shears
made of iron, whose prongs are brought to bear upon the stones, which
have holes bored in them. When one end of the rope is fastened to the
windlass, and the latter is turned round by working the handspikes, the
rope winds round the windlass, gets taut, and thus it raises the load to
the proper height and to its place in the work.

3. This kind of machinery, revolving with three sheaves, is called a
trispast. When there are two sheaves turning in the block beneath and
three in the upper, the machine is termed a pentaspast. But if we have
to furnish machines for heavier loads, we must use timbers of greater
length and thickness, providing them with correspondingly large bolts at
the top, and windlasses turning at the bottom. When these are ready,
let forestays be attached and left lying slack in front; let the
backstays be carried over the shoulders of the machine to some distance,
and, if there is nothing to which they can be fastened, sloping piles
should be driven, the ground rammed down all round to fix them firmly,
and the ropes made fast to them.

4. A block should then be attached by a stout cord to the top of the
machine, and from that point a rope should be carried to a pile, and to
a block tied to the pile. Let the rope be put in round the sheave of
this block, and brought back to the block that is fastened at the top of
the machine. Round its sheave the rope should be passed, and then should
go down from the top, and back