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The Catapult
The arrow is laid in the trough before the bowstring is stretched. (A,
B, fig. 8, p. 21)
The balistas made ready for use by turning the windlass. The windlass
pulls back the sliding trough, and the arrow resting in it, along the stock
of the engine, till the bow string is at its proper tension for discharging
the projectile. (Fig. 7, p. 19)
As the trough and the arrow are drawn back together, the arrow can be
safely laid in position before the engine is prepared for action.
The catch holding the bowstring, and the trigger for releasing it, are
fixed to the solid after end of the wooden trough. (Fig. 8, p. 21.)
The two ratchets at the side of the after-end of the trough travel over
and engage, as they pass along, the metal cogs fixed on either end of the
stock. (Fig. 8, p. 21)1
By this arrangement, the trough can be securely retained, in transit,
at any point between the one it started from and the one it attains when
drawn back to its full extent by the windlass.
As the lock and trigger of the ballista are fixed to the after end of
the sliding trough (G, fig. 8, p. 21), it will be realised that the arrow
could be discharged at any moment required in warfare, whether the bow
string was fully or only partially stretched.
In this respect the ballista differed form the crossbow, which it somewhat
resembled, as in a crossbow the bow string cannot be set free by the trigger
at any intermediate point, but only when it is drawn to the lock of the
weapon.
It will be seen that the balista derives its power from two arms; each
with its separate skein of cord and pair of winches.
These parts of the ballista are the same in their action and mechanism
as those of the catapult.
Fig. 8. (Opposite Page) The Mechanism of the Stock of an Arrow Throwing
Balista.
A. Side view of the stock, with the arrow laid in the sliding trough
before the bow string is stretched.
B. Surface view of the stock, with the arrow laid in the sliding trough
before the bow string is stretched.
C. Section of the fore-end of the stock, and of the trough which slides
in and along it.
1 When the bowstring has been released and
the arrow discharged, the ratchets are lifted clear of the cogs on the
stock of the engine. This allows the trough to be slid forward to its first
position as shown in A, B, fig. 8. p. 21. It is then ready to be drawn
back again for the next shot.
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 Roman
Ballista Plans
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Appendix >
Book of the Crossbow
> Ancient Projectile Engines
> Catapult > p.20 |
