The Ten Books on Architecture
and passed down over its lower sheaves, and so return to the bottom, and
are passed from the inside to the sheaves in the lowest block, and then
are brought up on the right and left, and return to the top and round
the highest set of sheaves.
7. Passing over these from the outside, they are then carried to the
right and left of the drum on the axle-tree, and are tied there so as to
stay fast. Then another rope is wound round the drum and carried to a
capstan, and when that is turned, it turns the drum and the axle-tree,
the ropes get taut as they wind round regularly, and thus they raise the
loads smoothly and with no danger. But if a larger drum is placed either
in the middle or at one side, without any capstan, men can tread in it
and accomplish the work more expeditiously.
8. There is also another kind of machine, ingenious enough and easy to
use with speed, but only experts can work with it. It consists of a
single timber, which is set up and held in place by stays on four sides.
Two cheeks are nailed on below the stays, a block is fastened by ropes
above the cheeks, and a straight piece of wood about two feet long, six
digits wide, and four digits thick, is put under the block. The blocks
used have each three rows of sheaves side by side. Hence three traction
ropes are fastened at the top of the machine. Then they are brought to
the block at the bottom, and passed from the inside round the sheaves
that are nearest the top of it. Then they are brought back to the upper
block, and passed inwards from outside round the sheaves nearest the
bottom.
9. On coming down to the block at the bottom, they are carried round its
second row of sheaves from the inside to the outside, and brought back
to the second row at the top, passing round it and returning to the
bottom; then from the bottom they are carried to the summit, where they
pass round the highest row of sheaves, and then return to the bottom of
the machine. At the foot of the machine a third block is attached. The
Greeks call it [Greek: epagôn], but our people "artemon." This block
fastened at the foot of the machine has three sheaves in it, round which
the ropes are passed and then delivered to men to pull. Thus, three rows
of men, pulling without a capstan, can quickly raise the load to the
top.
10. This kind of machine is called a polyspast, because of the many
revolving sheaves to which its dexterity and despatch are due. There is
also this advantage in the erection of only a single timber, that by
previously inclining it to the right or left as much as one wishes, the
load can be set down at one side.
All these kinds of machinery described above are, in their principles,
suited not only to the purposes mentioned, but also to the loading and
unloading of ships, some kinds being set upright, and others placed
horizontally on revolving platforms. On the same principle, ships can be
hauled ashore by means of arrangements of ropes and blocks used on the
ground, without setting up timbers.
11. It may also not be out of place to explain the ingenious procedure
of Chersiphron. Desiring to convey the shafts for the temple of Diana at
Ephesus from the stone quarries, and not trusting to carts, lest their
wheels should be engulfed on account of the great weights of the load
and the softness of the roads in the plain, he tried the following plan.
Using four-inch timbers, he joined two of them, each as long as the
shaft, with two crosspieces set between them, dovetailing all together,
and then leaded iron gudgeons shaped like dovetails into the ends of the
shafts, as dowels are leaded, and in the woodwork he fixed rings to
contain the pivots, and fastened wooden cheeks to the ends. The pivots,
being enclosed in the rings, turned freely. So, when yokes of oxen began
to draw the four-inch frame, they made the shaft revolve constantly,
turning it by means of the pivots and rings.
12. When they had thus transported all the shafts, and it became
necessary to transport the architraves, Chersiphron's son Metagenes
extended the same principle from the transportation of the shafts to the
bringing down of the architraves. He made wheels, each about twelve feet
in diameter, and enclosed the ends of the architraves in the wheels. In
the ends he fixed pivots and rings in the same way. So when the
four-inch frames were drawn by oxen, the wheels turned on the pivots
enclosed in the rings, and the architraves, which were enclosed like
axles in the wheels, soon reached the building, in the same way as the
shafts. The rollers used for smoothing the walks in palaestrae will
serve as an example of this method. But it could not have been employed
unless the distance had been short; for it is not more than eight miles
from the stone-quarries to the temple, and there is no hill, but an
uninterrupted plain.
13. In our own times, however, when the pedestal of the colossal Apollo
in his temple had cracked with age, they were afraid that the statue
would fall and be broken, and so they contracted for the cutting of a
pedestal from the same quarries. The contract was taken by one Paconius.
This pedestal was twelve feet long, eight feet wide, and six feet high.
Paconius, with confident pride, did not transport it by the method of
Metagenes, but determined to make a machine of a different sort, though
on the same principle.
14. He made wheels of about fifteen feet in diameter, and in these
wheels he enclosed the ends of the stone; then he fastened two-inch
crossbars from wheel to wheel round the stone, encompassing it, so that
there was an interval of not more than one foot between bar and bar.
Then he coiled a rope round the bars, yoked up his oxen, and began to
draw on the rope. Consequently as it uncoiled, it did indeed cause the
wheels to turn, but it could not draw them in a line straight along the
road, but kept swerving out to one side. Hence it was necessary to draw
the machine back again. Thus, by this drawing to and fro, Paconius got
into such financial embarrassment that he became insolvent.
15. I will digress a bit and explain how these stone-quarries were
discovered. Pixodorus was a shepherd who lived in that vicinity. When
the people of Ephesus were planning to build the temple of Diana in
marble, and debating whether to get the marble from Paros, Proconnesus,
Heraclea, or Thasos, Pixodorus drove out his sheep and was feeding his
flock in that very spot. Then two rams ran at each other, and, each
passing the other, one of them, after his charge, struck his horns
against a rock, from which a fragment of extremely white colour was
dislodged. So it is said that Pixodorus left his sheep in the mountains
and ran down to Ephesus carrying the fragment, since that very thing was
the question of the moment. Therefore they immediately decreed honours
to him and changed his name, so that instead of Pixodorus he should be
called Evangelus. And to this day the chief magistrate goes out to that
very spot every month and offers sacrifice to him, and if he does not,
he is punished.
CHAPTER III
THE ELEMENTS OF MOTION
1. I have briefly set forth what I thought necessary about the
principles of hoisting machines. In them two different things, unlike
each other, work together, as elements of their motion and power, to
produce these effects. One of them is the right line, which the Greeks
term [Greek: eutheia]; the other is the circle, which the Greeks call
[Greek: kyklôtê]; but in point of fact, neither rectilinear without
circular motion, nor revolutions, without rectilinear motion, can
accomplish the raising of loads. I will explain this, so that it may be
understood.
2. As centres, axles are inserted into the sheaves, and these are
fastened in the blocks; a rope carried over the sheaves, drawn straight
down, and fastened to a windlass, causes the load to move upward from
its place as the handspikes are turned. The pivots of this windlass,
lying as centres in right lines in its socket-pieces, and the handspikes
inserted in its holes, make the load rise when the ends of the windlass
revolve in a circle like a lathe. Just so, when an iron lever is applied
to a weight which a great many hands cannot move, with the fulcrum,
which the Greeks call [Greek: hupomochlion], lying as a centre in a
right line under the lever, and with the tongue of the lever placed
under the weight, one man's strength, bearing down upon the head of it,
heaves up the weight.
3. For, as the shorter fore part of the lever goes under the weight from
the fulcrum that forms the centre, the head of it, which is farther away
from that centre, on being depressed, is made to describe a circular
movement, and thus by pressure brings to an equilibrium the weight of a
very great load by means of a few hands. Again, if the tongue of an iron
lever is placed under a weight, and its head is not pushed down, but, on
the contrary, is heaved up, the tongue, supported on the surface of the
ground, will treat that as the weight, and the edge of the weight itself
as the fulcrum. Thus, not so easily as by pushing down, but by motion in
the opposite direction, the weight of the load will nevertheless be
raised. If, therefore, the tongue of a lever lying on a fulcrum goes too
far under the weight, and its head exerts its pressure too near the
centre, it will not be able to elevate the weight, nor can it do so
unless, as described above, the length of the lever is brought to
equilibrium by the depression of its head.
4. This may be seen from the balances that we call steelyards. When the
handle is set as a centre close to the end from which the scale hangs,
and the counterpoise is moved along towards the other arm of the beam,
shifting from point to point as it goes farther or even reaches the
extremity, a small and inferior weight becomes equal to a very heavy
object that is being weighed, on account of the equilibrium that is due
to the levelling of the beam. Thus, as it withdraws from the centre, a
small and comparatively light counterpoise, slowly turning the scale,
makes a greater amount of weight rise gently upwards from below.
5. So, too, the pilot of the biggest merchantman, grasping the steering
oar by its handle, which the Greeks call [Greek: oiax], and with one
hand bringing it to the turning point, according to the rules of his
art, by pressure about a centre, can turn the ship, although she may be
laden with a very large or even enormous burden of merchandise and
provisions. And when her sails are set only halfway up the mast, a ship
cannot run quickly; but when the yard is hoisted to the top, she makes
much quicker progress, because then the sails get the wind, not when
they are too close to the heel of the mast, which represents the
centre, but when they have moved farther away from it to the top.
6. As a lever thrust under a weight is harder to manage, and does not
put forth its strength, if the pressure is exerted at the centre, but
easily raises the weight when the extreme end of it is pushed down, so
sails that are only halfway up have less effect, but when they get
farther away from the centre, and are hoisted to the very top of the
mast, the pressure at the top forces the ship to make greater progress,
though the wind is no stronger but just the same. Again, take the case
of oars, which are fastened to the tholes by loops,--when they are
pushed forward and drawn back by the hand, if the ends of the blades are
at some distance from the centre, the oars foam with the waves of the
sea and drive the ship forward in a straight line with a mighty impulse,
while her prow cuts through the rare water.
7. And when the heaviest burdens are carried on poles by four or six
porters at a time, they find the centres of balance at the very middle