If strictly military work failed, there were endless civilian labors. Quadratus learned to use his spade almost as well as he could his pilum. He assisted in making and in repairing the great network of magnificent military roads leading to the frontiers. He worked in the legionary brick kilns, making bricks for the camps and the numerous small _castella_ used to hold back the onthrusting Germans. He helped also to rebuild a temple of Jupiter at the garrison town of Mogontiacum (Mayence), and later to tug up the stones for a new amphitheater in that city. If he had been attached to a Syrian legion, he and his comrades might even have been ordered out to repel an invasion not of Parthians but of the more devastating locusts. [Illustration: SHIELD OF THE LEGIONARY.] =274. Petty Officers in the Legions.=--All this experience came to him while he was earning his first promotions. Everybody in the legion--except those lowest and highest--had somebody, indeed, whom he could command while some one else could command him, and there was a very ingenious division and interlocking of power and responsibility. Petty officers abounded, and having approved himself, Quadratus became one of the _principales_ (high privates, and corporals)--first he became a _tesserarius_, “bearer of the watchword” for his century; then the “horn blower,” responsible often for important signals, then the _signifer_, the bearer of the small red flag (_vexillium_), surmounted with a small image of Victory, which was the standard of the cohort; then he was named _optio_ (“chosen” man by a centurion), a centurion’s deputy and assistant, entitled to rank as a real officer and responsible for the control of a large squad of men. [Illustration: MILITARY TRUMPET.] At last came one of the most important days of his life. At a general parade of the legion the commanding general (_legatus legionis_) announced that Quadratus was appointed centurion and solemnly intrusted him with the terrible vinestock. There was no danger he would show mercy to the raw recruits! =275. The Centurions: their Importance and Order of Promotion.=--Quadratus was now a member of that group of officers to which the Roman army owed the greater part of its entire discipline, morale, and efficiency. There were sixty centurions in every legion. They were usually self-made men, sturdy peasants’ sons like himself, who had risen from the ranks and then been selected by the general on account of merit.