Besides these machines, there are others constructed on the sling principle, like the mangona and mangonet, from which the word “gun,” originally “gon,” is probably derived. There are two stone balls at the Rotunda, Woolwich, which are said to have been thrown from a mangonel used in the defence of Kenilworth Castle in 1266. The onager or onagre is thought by some writers to be merely the old French name for the catapulta, while Grose gives a figure representing the onagre as a machine for slinging rocks. The trebuchet is a machine constructed on this principle (the swing and weighted lever), both for hurling and swinging a heavy stone against a rampart, breaching or breaking it down; it also threw barrels of Greek fire. Matthew Paris mentions this machine as peculiarly effective. This engine seems to be the mangonel under another name. The tolleno was used in siege operations to lift soldiers up on to a wall. During the centuries immediately preceding the introduction of firearms there were many machines invented for the hurling of darts and stones, used both on land and sea--the robinet, the espringal, ribandequin, a large crossbow, etc. The missile-casting engines used on ships of war were mounted on raised platforms. The late Emperor Napoleon III. had a trebuchet constructed after an ancient inscription, and this machine is now at Vincennes. Another called the warwolf is mentioned by several of the early writers, but they all differ considerably concerning it. Procopius describes it as a machine of the harrow family, for the defence of a gate; it seems to have been rather similar to the herse, used as a second defence after the portcullis had been forced. The falarica was for throwing fiery darts. It was used by the Saguntines, when the shaft was wrapped round with tow steeped in oil and smeared with sulphur and resin. This was ignited and the missile launched against the “pluteus,” a machine which was the prototype of the mediæval “sow” or “cat.” Many of these machines continued in use long after the introduction of firearms. A common feature in most ancient MSS. is that fancy names are freely applied to most of them, thus giving rise to much difficulty in their identification. PART XXI. MACHINES FOR ATTACKING BELEAGUERED PLACES. The castle of the middle ages up to the invention of the bombard was practically that of the ancient “castellum,” as far as defence was concerned, with outworks frequently of wood; and the means of attack lay in escalade, sapping and mining, the use of the battering-ram, or by a blockade. We now touch upon the machines used in attacks on fortified places, most of which have their prototypes during ancient times in the testudo, pluteus, tenebra, etc.