Men who had escaped shipwreck felt bound to make special offerings to the gods in testimony of their gratitude; sometimes hanging up in a neighbouring temple the garment in which they had been saved,[31] or shaving their hair—a custom Petronius justly calls the last vow of men who have saved nothing but their lives.[32] Rigid discipline was maintained on board the ships, and punishments of great severity inflicted on those who failed to keep proper ward and watch; nay, even the barbarous practice of “keel-hauling,” once not uncommon in the English service, was not wholly unknown to the ancients. The crews were generally composed of two classes; the mariners, who attended to the navigation and trimming of the sails, and the rowers. These offices were usually kept distinct, the mariners being rarely, except in cases of great emergency, compelled to labour at the oars.[33] The work of the rowers, to which we shall allude more particularly hereafter, was one of severe toil; hence, as in modern times, the music of the voice or the pipe stimulated the rowers to fresh exertion or tended to relieve the depressing monotony of their work.[34] Many ancient writers, and notably Xenophon, Polybius, and Arrian,[35] have left us interesting accounts of the way in which the rowers were trained; the practice of the Greeks and Romans, and especially that of the latter people, having been remarkable for its perfection in the execution of the most difficult manœuvres. [Sidenote: Master.] The master or pilot, whose place was in the stern, though not himself required to steer, was expected to understand the due management of the rudder and sails, the usual course of the winds, the indications in the sky of a change of weather, and the situation of the harbours most fitting for his vessel, or of the shoals the most to be avoided.[36] He was also expected to take proper cognizance of the omens offered by the sea-fowl and fishes, with divers other phenomena, as the murmuring of the floods, the dashing of waves against the shore, and other signs believed to import changes in the weather.[37] [Sidenote: Mate.] [Sidenote: Boatswain.] Next in authority to the master was the mate, whose place was at the prow of the ship, and who had charge of the tackle and of the rowers, who were placed by him on their proper seats.[38] With him was associated a third officer, whom we may call the boatswain and steward, as he gave the word to the rowers and distributed the rations.[39] There was also a fourth officer, whose especial duty it was to take heed of possible rocks or shoals, and to direct the ship at night by the aid of long poles. [Illustration: ST. PAUL’S SHIP, FROM THE WORK BY MR. SMITH OF JORDAN HILL.] [Sidenote: St. Paul’s ship.]