arge siege
train in classical literature is of the year 399 B.C., when Dionysius I.
of Syracuse, contemplating an expedition against Carthage, provided
himself with engines. From Sicily siege engines found their way some
years later into Greece; they were used by Philip of Macedon at the
siege of Byzantium in 340, and thereafter, as a natural consequence of
the regularizing or professionalizing of armies, artillery, as we may
call it, came into prominence and called into existence technical corps
to work it.

The war engines of the Romans, during the republic and early principate,
are of the same type as those of Alexander's successors in Greece. They
are usually classed as (a) catapults and (b) ballistae ([Greek:
lithoboloi]). The former were smaller and were used with arrows for what
is now called direct fire (i.e. at low angles of elevation); the latter
were large siege engines discharging heavy bolts or stones at a high
angle of elevation, like the modern howitzer. They were, of course,
principally siege engines, but the smaller natures of catapult appear in
field warfare from time to time, and eventually, during the early
principate, they are found as part of the regulation equipment of
infantry units. Both were constructed on the same principle.

[Illustration]

The essential parts of the catapult (see illustration) were the frame,
the propelling gear, the trough (corresponding to the modern barrel) and
the pedestal. The frame consisted of two horizontal beams forming top
and bottom sills, and four strong upright bars mortised into them. The
three open spaces or compartments, resembling narrow windows, between
these four uprights carried the propelling and laying gear. The
propelling gear occupied the two outer "windows." In each a thick skein
of cord or sinews was fastened to the top and bottom sills and tightly
twisted. Two stiff wooden arms were inserted in the two skeins, and a
specially strong bowstring joined the tips of these arms. In the middle
compartment was the hinged fore-end of the trough, which was at right
angles to the frame and at the back of it. The trough could be laid for
elevation by a movable prop, the upper end of which was hinged to the
trough, while the lower ran up and down a sort of trail fastened to the
pedestal. The whole equipment was laid for "line" by turning the frame,
and with it the trough, prop and trail by a pivot in the head of the
pedestal. Sliding up and down in the troug