The Catapult
The two small cogged wheels - with their checks - which are fitted on
the ends of the spindle (G, G), prevent the roller from reversing whilst
the arm is being wound down, fig. 194, next page.
H, H. The mortises cut in the sides of the catapult to receive the tenons
of the two uprights. Between the tops of these uprights is fixed the cross-bar
against which the arm of the catapult rests, or when released from its
catch strikes. The uprights and the cross-bar are shown in figs. 194, 195,
196, pp. 282, 284, 285.
It will be noticed that the mortises for the tenons of the uprights,
are placed well away from the circular openings in the sides of the catapult
through which the skein of cord passes. If these mortises were cut too
near the openings for the skein, the side-pieces of the catapult would
be weakened.
K, K, K. The mortises for the lower tenons of the three sloping supports
which prevent the two uprights,—and their cross-bar,—from giving way under
the blow of the released arm of the catapult, figs. 195, 202, pp. 284,
298.
The upper ends of the two side supports are mortised into the tops of
the uprights, to which they are also bolted, fig. 194, next page, and fig.
202, p. 298.
The top of the middle support is mortised into the centre of the cross-bar
that connects the uprights, fig. 195, p. 284, and fig. 202, p. 298.
Side View of the Catapult, Fig. 194, Next Page.
The arm (A) is here, ready to be wound down by the rope - 1 1/4 in.
in diameter - that is attached to it and also to the roller. The ends of
the rope are passed through holes in the winding roller and are then secured
by knots, F, F, fig. 193.
The upper part or bend of the rope is hitched by a slip-hook to a ring-bolt
which passes through the arm of the catapult. Fig. 200, p. 294, describes
the ring-bolt and the slip-hook.
B. The position of the arm when it is fully wound down by the roller.
The stone may be seen in the cup of the arm.
By pulling the cord (E), the arm is released from the slip-hook and
- taking an upward sweep of 90 degrees (see curved line of arrows) - returns
to its original position, as at A.
C. The position of the arm of the catapult at the moment when the stone
leaves it. The stone is projected upwards at an angle of about 45 degrees,
as represented by the straight line of small arrows that indicates its
flight after it leaves the arm at C. |