But these assertions, though they increase the difficulty of solving the intricate problem of how galleys, with more than one bank of oars, were propelled, can have no weight when opposed to practical experience. It is clear, without any testimony beyond our knowledge of the physical power of man, that no one man, however herculean, unless he had the aid of machinery, of which there is no proof, could work an oar in the manner described. Indeed, we know that in ancient galleys of every description, above the smallest uniremes, more men than one _were_ frequently employed upon the same oar. Such was the case in the celebrated Liburnian[386] galleys, already described. Here the question arises how many men could, with convenience, sit on each bench? Presuming that, in the case of an oar fifty-seven feet in length, one-third, or nineteen feet, remained within board, there would, allowing fifteen inches for each rower, be space for fifteen men to work at the one oar; and if the men who sat within six feet of the row-port were of no service, there is still ample space left to place ten effective rowers. If in comparatively modern times, when rowers were by no means crowded, eighteen inches for each man abreast was considered more than sufficient, we may infer that five men to an oar was far from an unfrequent practice in manning the state galleys of the Italian Republics. But while there is no difficulty in understanding how five or even ten men could be rendered serviceable in working the oars of single-banked galleys, a great difficulty arises when we inquire how that number of men could effectively handle the upper bank oars of the quadriremes and quinqueremes. On these and on many other matters the accounts of the ancients are conflicting: nor do the imperfect illustrations on ancient monuments and on coins materially assist in their elucidation. Assured of the fact that there were many vessels of much larger dimensions than even quinqueremes propelled by oars, we have to consider _how this was done_. Now the only mode of arriving at correct conclusions on this, the most conflicting and intricate of all the problems connected with shipping which ancient authors have left for solution, is to trace the progress of the galleys themselves, from the single-banked craft or unireme upwards. [Sidenote: Single-banked galleys.] With the exception of the extraordinary Liburnian galleys, every account extant leads to the conviction that the single-banked galleys of the Venetians and Genoese resembled in many respects those of the Romans and ancient Greeks. Drawings of Venetian galleys, to which references will hereafter be made, have been preserved, but, as no detailed account of them exists, we are obliged to seek for information from a writer of a comparatively modern date.[387] [Sidenote: French galley.]