“Rowing. This practice was anciently directed by a person called Celeustes, who gave the signal for the rowers to strike, and encouraged them by his song or cry. This song, called the celeusma, was either sung by the rowers, or played upon instruments, or effected by a symphony of many, or striking sonorous tones. The commander of the rowers, called Hortator Remigum, Pausarius, and Portisculus, was placed in the middle of them. He carried a staff, with which he gave the signal, when his voice could not be heard. The Corinthians first introduced the use of many ranks of oars. The method consisted in the rowers sitting obliquely one above another in this fashion….

They did not sit, but stood inclined. Ossian mentions the rowing song; and the Anglo-Saxon, batswan, or boatswain, as they called him, had also a staff to direct the rowers ; nor is one man, rowing with sculls, one in each hand, modern, the Greeks having boats on purpose, called ampheres, long and narrow. Mention is made of rowing with the face to the prow, as usual with our ancestors, but it must be pushing not drawing the oar. The oar upon the Etruscan vases is of the form of a very narrow pyramid from top to bottom. Evelyn says, that Andrew Baldarius was the inventor of oars, applied to large vessels for fighting.”
[Encyclopedia of Antiquities; and elements of Archaeology, Classical and Mediæval, Vol.1, Fosbroke, 1825]