Officers must know an infinite number of things that a deck hand need not trouble himself to learn. They must know how to manœuvre to avoid collision, an important matter in these days of many ships and busy sea lanes. They must know the rules of the road, for every ship one passes close to must be signalled in order that her officers may know exactly what the approaching ship is planning to do. An officer must know a hundred different arrangements of lights at night, which may mark ships under sail, under power, at anchor, with barges in tow, ships not under command, buoys, lighthouses, cable vessels, pilot ships, fishermen with their gear drifting about them, open boats, and a variety of other things. He should be able to signal in the International Code with a flashlight. He must know how to handle his ship in heavy weather in order that her hull shall not be unduly strained, her upper works unduly battered, or her cargo shifted. He should be adept at handling his ship around a dock, and must be equally adept at making her fast alongside pier or quay. He must know what to do in case of collision, in case of fire, in case any of a score of contingencies arise. He must be familiar with first aid and the use of medicines, for few ships carry doctors. He must be seaman enough for all his crew, for on him rests a great responsibility—the responsibility for a great and costly machine, for valuable cargoes, for the health, and even for the lives, of many men. Should a man ashore be employed to manage a factory as costly as a ten-thousand-ton ship, with an output as valuable as the cargoes of such a ship, he would be paid many times what a captain is paid, and, should fire destroy his factory or tornado crush it, he would probably be given the insurance money in order to build another. Not so the captain. His responsibility is as great or greater; his experience and ability must be at least as great; his pay is little; and should a tempest tear his ship apart beneath him he is likely to be doomed for ever after to stay ashore, a broken captain, and probably a broken-hearted man. The captain of a sailing ship must be familiar with many things that the captain of a steamer need not know. As in practically every other line of modern endeavour, the handling of ships has developed specialists. The chief engineer is responsible for the motive power of ships to-day. And he need know nothing more than how to operate the machinery. The captain need only know, so far as power is concerned, whether he wants the propeller to drive him ahead or astern and how fast, and how to use his propellers in tight places. The argument as to who is more important to the ship, despite its futility, still sometimes waxes strong. Both are essential, for the engineer harnesses the steam that drives the ship. He must be subject to the commands of the captain, who formerly had need himself to know how to harness power by means of sails, which were his engines.