_Criticism._--This engine was moved into position on rollers and then props were placed under its sides to adjust the range of the projectile. The end of the arm was secured by the notch of the large iron catch and was released by striking down the handle of the catch with a heavy mallet. The arm is, however, too long for the height of the cross-bar against which it strikes and would probably break off at its centre. The hollow for the stone is much too large, as a stone big enough to fit it could not be cast by a weapon of the dimensions shown in the picture. _From an Illustrated Manuscript, Fifteenth Century (No. 7239), Bibl. Nat. Paris._] The mediæval catapult was usually fitted with an arm that had a hollow or cup at its upper end in which was placed the stone it projected, as shown above in fig. 5.[4] I find, however, that the original and more perfect form of this engine, as employed by the Greeks and ancient Romans, had a sling, made of rope and leather, attached to its arm.[5] (Fig. 6, following page.) [4] See also _The Crossbow_, _etc._, Chapters LV., LVI., illustrations 193 to 202. [5] In mediæval times catapults which had not slings cast great stones, but only to a short distance in comparison with the earlier weapons of the same kind that were equipped with slings. I can find no allusions or pictures to show that during this period any engine was used with a sling except the trebuchet, a post-Roman invention. All evidence goes to prove that the secret of making the skein and other important parts of a catapult was in a great measure lost within a couple of centuries after the Romans copied the weapon from their conquered enemies the Greeks, with the result that the trebuchet was introduced for throwing stones. The catapult was gradually superseded as the art of its construction was neglected, and its efficiency in sieges was therefrom decreased. The catapults of the fifth and sixth centuries were very inferior to those described by Josephus as being used at the sieges of Jerusalem and Jotapata (A.D. 70, A.D. 67), p. 37. [Page 12] [Illustration: FIG. 6.--SKETCH PLAN OF A CATAPULT FOR SLINGING STONES ITS ARM BEING PARTLY WOUND DOWN. Approximate scale: ¼ in. = 1 ft.] [Page 13] The addition of a sling to the arm of a catapult increases its power by at least a third. For example, the catapult described in Chapters LV., LVI., of my book,[6] will throw a round stone 8 lbs. in weight, from 350 to 360 yards, but the same engine with the advantage of a sling to its arm will cast the 8-lb. stone from 450 to 460 yards, and when its skein is twisted to its limit of tension to nearly 500 yards.