[Illustration: ANCIENT GALLEY FIGHT, FROM POMPEII.]
The benches on which the rowers sat ran from the vessel's side to timbers which, inclined at an angle of about 64° towards the ship's stern, reached from the lower to the upper deck. These timbers were, according to Graser, called the diaphragmata. In the trireme each diaphragma supported three, in the quinquereme five, in the octireme eight, and in the famous tesseraconteres forty seats of rowers, who all belonged to the same 'complexus,' though each to a different bank. In effect, when once the principle of construction had been established in the trireme, the increase to larger rates was effected, so far as the motive power was concerned, by lengthening the diaphragmata upwards, while the increase in the length of the vessel gave a greater number of rowers to each bank. The upper tiers of oarsmen exceeded in number those below, as the contraction of the sides of the vessel left less available space towards the bows.
Of the length of the oars in the trireme we have an indication in the fact that the length of supernumerary oars ([perinheô]) rowed from the gangway above the thranites, and therefore probably slightly exceeding the thranitic oars in length, is given in the Attic tables as 14 feet 3 inches. The thranites were probably about 14 feet. The zygite, in proportion to the measurement, must have been 10-1/2, the thalamite 7-1/2 feet long. Comparing modern oars with these, we find that the longest oars used in the British navy are 18 feet. The University race is rowed with oars 12 feet 9 inches. The proportion of the loom inboard was about one third, but the oars of the rowers amidship must have been somewhat longer inboard. The size of the loom inboard preserved the necessary equilibrium. The long oars of the larger rates were weighted inboard with lead. Thus the topmost oars of the tesseraconteres, of which the length was 53 feet, were exactly balanced at the rowlock.
The Attic trireme was built light for speed and for ramming purposes. Her dimensions, so far as we can gather them from the scattered notices of antiquity, were probably approximately as follows:--length of rowing space ([hegkôpon]), 93 feet; bows, 11 feet; stern, 14 feet; total, 118 feet; add 10 feet for the beak. The breadth at the water-line is calculated at 14 feet, and above at the broadest part 18 feet, exclusive of the gangways; the space between the diaphragmata mentioned above was 7 feet. The deck was 11 feet above the water-line, and the draught about 8 to 9 feet. All the Attic triremes appear to have been built upon the same model, and their gear was interchangeable. The Athenians had a peculiar system of girding the ships with long cables ([hypozhômata]), each trireme having two or more, which, passing through eyeholes in front of the stem-post, ran all round the vessel lengthwise immediately under the waling-pieces. They were fastened at the stern and tightened up with levers. These cables, by shrinking as soon as they were wet, tightened the whole fabric of the vessel, and in action, in all probability, relieved the hull from part of the shock of ramming, the strain of which would be sustained by the waling-pieces convergent in the beaks. These rope-girdles are not to be confused with the process of undergirding or frapping, such as is narrated of the vessel in which St. Paul was being carried to Italy. The trireme appears to have had three masts. The mainmast carried square sails, probably two in number. The foremast and the mizen carried lateen sails. In action the Greeks did not use sails, and everything that could be lowered was stowed below. The mainmasts and larger sails were often left ashore if a conflict was expected.