Ancient Siege Engines
The ballista and the catapult
derived their projectile force from the recoil of tightly twisted
cordage, while the trebuchet
owed its power to the utilisation of the force of gravity of a heavy weight.
Though the construction of these engines was quite distinct, and the
one kind projected stones and the other arrows, their respective names
have been so carelessly used by many mediaeval as well as later writers,
that it is often impossible to tell which class of engine an author alludes
Even among the earliest historians, the name ' ballista ' was frequently
bestowed on any large siege weapon that discharged missiles - whether the
missiles were bolts or stones.1
The following names were commonly, and often indiscriminately applied
to the ancient and medieval engines
that projected stones and arrows of large size :
||Engin a verge
Though so many names suggest that there were numerous varieties of siege
engines, this was not the case.
All these names refer at most to four distinct weapons, and these I
shall presently describe.
Besides the names given above, others were coined for certain well-known
machines which from their power or accuracy became popular among the soldiery.
For instance we read of the Warwolf , the Wild-cat, the Bull-slinger, the
Ill-neighbour, the Queen, the Lady and so forth. Just as in our day an
artilleryman will bestow particular care on the appearance of a gun in
the performances of which he takes pride, so doubtless the ancients favoured
one or other engine which had distinguished itself in action, and called
it by some fanciful name to record its success.
Many of the illustrations of balistas and catapults to be found in late
1 The catapult is often described as having
been employed for throwing heavy javelins as well as great stones. In my
opinion, based on practical experience, the mechanism of a catapult could
not possibly have been adapted for projecting a javelin. Its construction
shows that this engine was never intended for such a purpose. The name
catapult was, however, often applied to the ballista. This confusion was
no doubt the cause of mistakes on the part of those compilers who were
ignorant of the mechanical details of the two weapons. In the large picture
of a Roman catapult painted by Sir E. Poynter, P.R.A., the artist has depicted
a weapon that actually combines in its mechanism the parts of a catapult
a trebuchet and a spring engine.
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