One point we may as well make clear at once, viz., that whatever was the vessel the ancients invariably went upon the principle, _One man, one oar_. Volumes have been wasted in attempts to prove that the arrangement of the ancient galleys with respect to propulsion were identical with, or very similar to, those of the mediaeval galleys of Genoa or Venice. But the mediaeval galleys were essentially _monocrota_, or one-banked vessels, though they may have been double-banked or treble-banked in the sense that two or three men were employed upon one oar. [Illustration: BAS-RELIEF OF ANCIENT GREEK ROWING BOAT.] Another distinction that it is necessary to note with reference to the ancient galleys is that they were called _Aphract_ or _Kataphract_ according as the upper tier of rowers was unprotected and exposed to view, or fenced in by a bulwark stout enough to protect them from the enemy's missiles. The system of side planking is observable as already adopted in some of the Egyptian vessels, though of the Greeks the Thasians are credited with the invention. In the year 1834, during the process of excavating some ground for new public buildings in the Piraeus near Athens, some engraved stone slabs were found built up in a low wall which had been uncovered. These were happily preserved and deciphered, and were found to be records of the dockyard authorities of the Athenian admiralty in the second and third centuries before Christ. Many interesting details were thus brought to light which were set in order by the illustrious scholar Boeckh in his volume entitled 'Urkunden ueber das Seewesen des attischen Staates.' His pupil Dr. Graser has carried on his researches by the examination of innumerable coins, vases, etc., and has rescued the subject from much of the obscurity which enveloped it. The following description of the trireme, based upon his labours, is quoted, by permission, from the new edition of the 'Encyclopaedia Britannica,' vol. xxi. pp. 806, 807.