The sweep of an oar is measured by its length, and would require a certain defined space for its movement, irrespective of the number of men at work upon it. The single-banked French galley already described was one hundred and fifty feet long, having twenty five benches on each side, requiring a length of one hundred feet. All other accounts, as well as experience, show that the benches were, and required to be, three feet apart: and, allowing one foot for the breadth of the bench, each oar would require a space of four feet in a horizontal line. According to the General’s theory there would be thirty oar-ports on each bank, which, allowing for their obliquity, would require the gallery attached to the side of his galley to be somewhere about two hundred feet in length for the accommodation of the rowers. No doubt such a vessel could be built, but it is very questionable if any such vessel _ever was built_. Ptolemy Philopator’s ship would have required two thousand oar-ports on each side, to afford employment to her rowers. There is, however, another equally valid objection to the General’s scheme: a bank of oars means something whereby one class of galleys could be clearly distinguished from another class. Ships of war, up to a comparatively recent period, were rated as mounting so many guns, just as ancient galleys were rated by their banks of oars; the one measured the fighting, the other the propelling power. But if, according to the General’s plan, triremes or quinqueremes were known by the number of banks, what was the measure of vessels of the larger size? for he does not profess to work any galley on his plan with more than five tiers; nor does he maintain that the size of his galley was measured by the number of her oars, which would depend upon her length. In whatever way this scheme is examined it will be found to be altogether untenable. [Sidenote: Charnock’s theory.] Charnock, in his “History of Marine Architecture,”[392] has evidently devoted more space than thought to the elucidation of this intricate subject. While he, with all other writers on the subject, accurately describes “uniremes” as “those galleys or vessels which had only one row of oars extending between their masts, or perhaps the entire length of the vessel,” he breaks down at the first step beyond a unireme, when he says that “the biremes had one tier of oars between their masts, and another abaft the main or principal mast.” Indeed, all theories must necessarily fail which cannot be made applicable to vessels of every description; and it is no solution of the difficulty to deny, as Mr. Charnock and others have done, the existence of vessels beyond a certain size, when it is found that a theory practicable within certain limits would be altogether impracticable if carried beyond them.