During the early period of the republic, the standing army in time of peace usually consisted of only four legions, two of which were commanded by each consul, and they were relieved by new levies every year, the soldiers then serving without any pay beyond their mere subsistence. But this number was afterwards greatly augmented, and the inconvenience of raw troops having been experienced, a fixed stipend in money was allowed to the men, and they were constantly retained in the service. The legion usually consisted of three hundred horse, and three thousand foot: the different kinds of infantry which composed it were three, the _hastati_, _principes_, and _triarii_. The first were so called because they fought with spears: they consisted of young men in the flower of life, and formed the first line in battle. The _principes_ were men of middle age who occupied the second line. The _triarii_ were old soldiers of approved valor, who formed the third line. There was a fourth kind of troops, called _velĭtes_ from their swiftness and agility: these did not form a part of the legion, and had no certain post assigned them, but fought in scattered parties, wherever occasion required, usually before the lines. The imperial eagle was the common standard of the legion; it was of gilt metal, borne on a spear by an officer of rank, styled, from his office, _aquilifer_, and was regarded by the soldiery with the greatest reverence. There were other ensigns, as A. B. C. D. in the frontispiece. The only musical instruments used in the Roman army, were brazen trumpets of different forms, adapted to the various duties of the service. The arms of the soldiery varied according to the battalion in which they served. Some were equipped with light javelins, and others with a missile weapon, called _pilum_, which they flung at the enemy; but all carried shields and short swords of that description, usually styled cut and thrust, which they wore on the right side, to prevent its interfering with the buckler, which they bore on the left arm. The shield was of an oblong or oval shape, with an iron boss jutting out in the middle, to glance off stones or darts; it was four feet long and two and a half broad, made of pieces of wood joined together with small plates of iron, and the whole covered with a bull's hide. They were partly dressed in a metal cuirass with an under covering of cloth; on the head they wore helmets of brass, either fastened under the chin, with plates of the same metal, or reaching to the shoulders, which they covered and ornamented on the top with flowing tufts of horse hair.