Of machines formed on the sling principle, that called Onager (plates vii. and viii.) may be regarded as typical of all the rest. Its force entirely depended upon the torsion of a short thick rope, acting upon a lever which described an arc of a vertical circle. The lever had attached to its free extremity a sling, or sometimes it merely terminated in a spoon-shaped cavity. When bent back, it was secured by a catch or trigger, and charged with a stone. On starting the catch by a blow with a mallet, the lever described its arc of a circle with great velocity, and projected the stone to a considerable distance. I shall now briefly describe some of the portable missive weapons which have been used by different nations. ~Javelin.~ ~Arms of the early Romans.~ ~Aid to projection.~ The Javelin, or dart, variously modified, is known under several names. The ancients were well acquainted with it. In the Scriptures, we have frequent notice of it; and the ancients instituted javelin matches. It would appear that the javelin used on horseback was about five feet and a half long, and headed with steel, usually three-sided, but sometimes round. The Roman Cavalry, after the conquest of Greece, were armed much like the Infantry, carrying swords, shields, and javelins with points at both ends. Sometimes, in order to launch it with greater force, it was not propelled by the unaided arm, but by the assistance of a thong fastened to its butt end; and we are informed that the Greeks and Romans projected darts and javelins by the assistance of a sling or strap, girt round their middle. ~Djereed.~ ~Pilum.~ ~Australian mode.~ ~Harpoon.~ At the present time, a javelin, termed Djereed, is used with considerable effect by certain oriental nations, who invariably employ it on horseback. The Roman infantry possessed a weapon of the javelin kind, termed Pilum, every man of the legionary soldiers carrying two. The point of this weapon being very long and small, was usually so bent at the first discharge as to be rendered useless afterwards. With every improvement that the javelin was susceptible of, it never could acquire a long range; hence we find, that as Archery became developed, the use of the weapon declined. Amongst savage nations, the use of the javelin is very common, but the inhabitants of Australia have a manner of throwing it altogether peculiar to themselves, not throwing it while poised at the balance, but projecting it by means of a stick applied at the butt end. This contrivance accomplishes a great increase of range, but does not contribute to accuracy of direction. At short distances, the penetrating force of the javelin is considerable, as is learned from the act of harpooning a whale, a harpoon being merely a javelin. THE SLING. ~Slings mentioned in Judges. B. C. 1406.~ ~Slings used B. C. 1406.~