The Roman legion, whether it was composed of four thousand men, as in the early ages of the republic or six thousand, as in the time of Augustus, of was divided into ten cohorts, and each cohort was composed of Hastati, Principes, Triarii, and Velites. The soldiers of the first line, called Hastati, consisted of youths in the bloom of manhood, and were distributed into fifteen companies or maniples. Each company contained sixty privates, two centurions, and a standard-bearer. Two thirds were heavily armed, and bore the long shield, the remainder carried only a spear and light javelins. The second line, the Principes, was composed of men in the full vigor of life, divided also into fifteen companies, all heavily armed, and distinguished by the splendor of their equipments. The third body, the Triarii, was also composed of tried veterans, in fifteen companies, the least trustworthy of which were placed in the rear. These formed three lines. The Velites were light- armed troops, employed on outpost duty, and mingled with the horsemen. The Hastati were so called because they were armed with the hasta; the Principes, for being placed so near to the front; the Triarii, from having been arrayed behind the first two lines as a body of reserve, armed with the pilum, thicker and stronger than the Grecian lance,--four and a half feet long, of wood, with a barbed head of iron,--so that the whole length of the weapon was six feet nine inches. It was used either to throw or thrust with, and when it pierced the enemy's shield, [Footnote: Liv. viii. 8.] the iron head was bent, and the spear, owing to the twist in the iron, still held to the shield. [Footnote: Plut. Mar. 25.] Each soldier carried two of these weapons. [Footnote: Polyb. vi. 23.] The Principes were in the front ranks of the phalanx, clad in complete defensive armor,--men in the vigor of strength. The Pilarii were in the rear, who threw the heavy pilum over the heads of their comrades, in order to break the enemy's line. In the time of the empire, when the legion was modified, the infantry wore cuirasses and helmets, and two swords; namely, a long one and a dagger. The select infantry carried a long spear and a shield, the rest a pilum. Each man carried a saw, a basket, a mattock, a hatchet, a leather strap, a hook, a chain, and provisions for three days. The Equites wore helmets and cuirasses, like the infantry, with a broad sword at the right side, and in their hand a long pole. A buckler swung at the horse's flank. They were also furnished with a quiver containing three or four javelins. [Sidenote: The artillery.] [Sidenote: The Testudo.] [Sidenote: The Helepolis.] [Sidenote: The Turris.] [Sidenote: Scailing-ladders.]