[*] There is some reason for believing that an Athenian trireme was kept in service for many years, with only incidental repairs, and then could still be counted as fit to take her place in the line of battle. The upper deck of the trireme is about eleven feet above the harbor waves, but the lowest oar holes are raised barely three feet. Into the intervening space the whole complicated rowing apparatus has to be crammed with a good deal of ingenuity. Running along two thirds of the length of the hull nearly the whole interior of the vessel is filled with a series of seats and foot rests rising in sets of three. Each man has a bench and a kind of stool beneath him, and sits close to a porthole. The feet of the lowest rower are near the level of the water line; swinging two feet above him and only a little behind him is his comrade of the second tier; higher and behind in turn is he of the third.[*] Running down the center of the ship on either side of these complicated benches is a broad, central gangway, just under the upper deck. Here the supernumeraries will take refuge from the darts in battle, and here the regular rowers will have to do most of their eating, resting, and sleeping when they are not actually on the benches or on shore. [*] The exact system by which these oar benches were arranged, the crew taught to swing together (despite the inequalities in the length of their oars), and several other like problems connected with the trireme, have received no satisfactory solution by modern investigators. 108. The Rowers’ Benches of a Trireme.—With her full complement of rowers the benches of the _Invincible_ fairly swarm with life. There are 62 rowers to the upper tier (_thranites_), 58 for the middle tier (_zygites_), and 54 for the lower (_thalamites_), each man with his own individual oar. The _thranites_ with the longest oars (full 13 feet 6 inches) have the hardest pull and the largest pay, but not one of the 174 oarsmen holds a sinecure. In ordinary cruising, to be sure, the trireme will make use of her sails, to help out a single bank of oars which must be kept going almost all the time. Even then it is weary work to break your back for a couple of hours taking your turn on the benches. But in battle the trireme almost never uses sails. She becomes a vast, many-footed monster, flying over the foam; and the pace of the three oar banks, swinging together, becomes maddening. Behind their bulwarks the rowers can see little of what is passing. Everything is dependent upon their rowing together in absolute rhythm come what may, and giving instant obedience to orders. The trireme is in one sense like a latter-day steamer in her methods of propulsion; but the driving force is 174 straining, panting humans, not insensate water vapor and steel.