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FIG 7. – CATAPULT (WITH A SLING). Side view of frame and mechanism.
Scale : ½ in. = 1 ft.
Ammianus writes of the catapult 1:
`In the middle of the ropes2 rises a wooden arm like a chariot
pole . . . to the
top of the arm hangs a sling . . . when the battle is commenced a round
stone is set
in the sling . . . four soldiers on each side of the engine wind the
arm down till it is
almost level with the ground . . . when the arm is set free it springs
up and hurls
forth from its sling the stone, which is certain to crush whatever
it strikes. This
engine was formerly called the “scorpion,” because it has it sting
erect,3 but later
ages have given it the name of Onager, or wild ass, for when wild asses
they kick the stones behind them.’
Fig. 7. – Catapult (with a sling) (See previuos page)
A. The arm at rest, ready to be wound down by the rope attached
to it and
also to the wooden roller of the windlass. The stone may be seen
in the sling.
The upper end of the pulley rope is hitched by a metal slip-hook (fig.6)
to a ring-bolt secured to the arm just below the sling.
B. The position of the arm when
fully wound down by means of the
windlass and rope. See also EE, fig. 8.
C. The position of the arm at
the moment the stone D leaves the sling,
which it does at an angle of about 45 degrees.
E. By pulling the cord E the arm B is at once released from the
and, taking an upward sweep of 90 degrees, returns to its original
position at A.
THE SLING (OPEN)
F. Its fixed end which passes through a hole near the top of the
G. The leather pocket for the stone.
H. The loop which is hitched over the iron pin at the top of the
the stone is in position in the sling, as shown at A and B, fig. 7.
1 Roman History, Book XXIII., Chapter
2 i.e. in the middle of the twisted skein
formed of ropes of sinew or hair.
3 The upright and tapering arm of a catapult,
with the iron pin on its top for the loop of the sling, is here fancifully
likened to the erected tail of an angry scorpion with its sting protruding.
FIG. 8.-- CATAPULT (WITH A SLING). Surface view of frame and
mechanism. Scale : .in. = 1 foot.
The arm EE is here shown wound down to its full extent. (Compare
with B, fig. 7.)
I. I. }
II. II. } The side pieces
III. IV. The large cross-pieces
V. The small cross-pieces
The ends of the cross-piece beams are stepped into the side pieces.
AA. The skein of twisted cord.
BB. The large winding wheels. The skein
is stretched between these
wheels, its ends passing through the
sides of the frame, and then through
wheels and over their cross-bars. (fg. 12.)
By turning with a long spanner (fig.
6.) the squared ends of the
spindles DD, the pinion wheels CC rotate the large wheels BB and cause
to twist the skein AA, between the halves of which the arm EE is placed.
FF. The wooden roller which winds down the arm EE. (fig. 6.)
The roller is revolved by four men (two on each side of the engine)
long spanners on the squared ends of the iron spindle GG.
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