h was a block, fitted with a
trigger mechanism, through which passed the middle of the bowstring. The
pedestal was a strong and solid upright resting upon, and strutted to, a
framework on the ground; its upper end, as mentioned above, took the
pivot of the frame and the head of the trail.

On coming into action the machine was laid for direction and elevation.
The block and with it the bowstring was next forced back against the
resistance of the twisted skeins to the rear end of the trough, this
being effected by a windlass attachment. The trigger being then pressed
or struck with a hammer, the bowstring was released from the block, the
stiff arms were violently brought back to the frame by the untwisting of
the skeins, and the arrow was propelled through the centre "window" with
great velocity. A small machine of the type described weighed about 85
lb., and sent a "three-span" (26-in.) arrow weighing 1/2 lb. at an
effective man-killing velocity somewhat over 400 yds.

The ballista was considerably larger and more expensive than this. In
Scipio's siege train, at the attack of New Carthage (Livy xxvi. 47. 5),
the number of the ballistae was only one-sixth that of the catapults. In
the ballista the rear end of the trough (which projected in front of the
frame) always rested upon the ground, or rather was fixed to the
framework of the pedestal--which was a heavy trestle construction--and
the trough was thus restricted to the angle of elevation, giving the
maximum range (45 deg.). Even so the range was not appreciably greater
than that of a catapult, and in the case of the largest ballistae
(ninety-pounder) it was much less. These enormous engines, which, once
in position, could not be laid on any fresh target, were used for
propelling beams and stones rather than for shooting arrows, that is,
more for the destruction of material than for man-killing effect. The
skeins that supplied the motive force of all these engines were made of
the sinews of animals, twisted raw hide, horsehair rope, and, in at
least one celebrated case, of women's hair. In 146 B.C., the authorities
of Carthage having surrendered their engines to the Romans in the vain
hope of staying their advance, new ones were hurriedly constructed, and
the women and virgins of the city cut off their hair to supply the
needed skeins.

The modern implement known as a "catapult" is formed by a forked stick,
to the forks of which are attached the ends of a piece of e