A summary of the history, construction and effects in warfare of the projectile-throwing engines of the ancients, with a treatise on the structure, power and management of Turkish and other Oriental bows of mediæval and later times

by Sir Ralph Payne-Gallwey

The slip-hook will release the arm of the engine at any moment, whether it is fully or only partially wound down by the windlass.

The slip-hook of the large catapult shown in [fig. 6], p. 12, has a handle, i.e. lever, 10 inches long, the point of the hook, which passes through the eye-bolt secured to the arm, being one inch in diameter.

Fig. 11.—A Spring Engine with a Sling attached to its Arm, which cast Two Stones at the Same Time.

From ‘Il Codice Atlantico,’ Leonardo da Vinci. 1445–1520.

Fig. 12.—The Skein of Cord.

A. The skein as first wound over the cross-bars of the large wheels (shown in section) of the winches.

B. The skein with the butt-end of the arm (shown in section) placed between its halves.

C. The skein as it appears when tightly twisted up by the winches. Compare with AA, [fig. 8], p. 16.