K. 
round the second range of pulleys from the inner to the outer side, they are carried to the 
second range of pulleys of the higher (trochlea), which passing over, they return to the 
lowest: from the lowest they are carried to the upper; and passing round the uppermost (pulleys), 
return to the bottom of the machine. 
At the root of the machine is placed a third trochlea (P), which is called by the Greeks 
ebagonta; by us, artemon. This trochlea is bound to the foot of the machine, and has three 
pulleys, around which the ropes passing, are conveyed thence to the men (R) who are to pull 
them; and so by the power of three rows of men, the weight is, without a capstan, quickly 
taised to the top. This kind of machine is called polyspaston, because it has many pulleys, 
which produce facility and expedition. The using of one beam has this convenience, that the 
load may be put as much as you will either before or declining to the right or left side. 
All the machines before described, are adapted not only to these purposes, but allo to the 
loading and unloading of ships; some being disposed erect, others horizontally in verlatile 
carchesia; so likewise, without erecting beams, by a similar management of ropes and 
trochleas on the plain ground, ships are drawn alhore. 
(a*) Our workmen also sometimes make use of a ma¬ 
chine similar to this, being a long beam fixed at the bottom 
in a wheel, as its base; and having sheaves of pulleys at 
the top, by which stones or timbers are raised to the height 
of the work. 
As Perrault's figures of these machines appear to be 
accurate and intelligibly drawn, I have made use of them 
so far as they accord with my ideas, altering them only 
where I imagined they were misconceived or erroneous. 
(4*) Vitruvius speaks of the charchesum, at the lalt 
chapter of this book, as being a very simple machine, and 
usually made by the soldiers themselves. Some part at 
the top of a ship's mast was called by the same appella¬ 
tion, as was also a particular kind of cup. It is supposed 
to have been an upright beam, with another lying hori-¬ 
zontally acros the top, and moveable upon a hinge up¬ 
ward and downward, as well as having a horizontal 
motion around; by these motions therefore it could raile 
things from the ground, and then convey them to their 
intended situation. 
The French grue is a machine of this kind, and is very 
serviceable in building, but is not used in this country. 
It may not therefore be useless to describe it, and give à 
representation thereof. AB, Fig. LXXVII. is a post lup¬ 
ported by the struts and frame C; on the pivot Areits à 
long beam DD, fixed to the timbers EE and FF, and 
supported from them obliquely by braces GG. In the 
timbers EE and FF (each of which consists of two 
pieces bolted together laterally) are cut round holes at 
HH, large enough to admit the post AB, which is cut 
cylindrically in those places: by these means the whole 
triangular frame FDF rests, and may be turned upon the 
pivot A, and is preserved in its position by the timbers EE 
and FF, embracing the post at HH. From the timber FF 
hangs a cylindric wheel I, large and broad enough for two 
or three men to walk in it: around the axis K of which 
is wound a rope, which passing through the timber FF to 
a pulley at the end of the timber E, is carried to the upper 
end of the long beam DD; where passing round a 
pulley D, it descends, and is fastened to the weight L to 
be raised. The men then, by walking in the wheel l, 
turn it, and wind the rope round the axis K, thereby 
raising the weight; which, when arrived at the height re¬ 
quired, is, by turning the machine on the pivot 4, con¬ 
veyed to its place in the work. 
Perault has, in his trandlation of Vitruvius, given an 
acount of a machine to raise weights, that adts upon the 
principle of the roler, having (as he mistakingly asserts) 
no friction: a model of it is kept in the cabinet of the 
King of France. It consists of a long column 4B, 
Fig. LXXVIII. resting at bottom on a pivot A, and lup¬