_This type of ship is eliminating the whaleback on the Great Lakes, and is used largely to transport ore and grain._] In a modern harbour there is another type of boat more numerous than ferries, and, from the point of view of the deep-sea sailor, more important. This is the tug. A tug is a towboat, and once a sea-going ship has reached a harbour, she is largely dependent on that harbour’s tugs. In appearance, at least, European tugs are very different from American. In British and German and French ports, and elsewhere on the continent, one sees many paddle-wheel tugs—a thing unknown, or nearly so, in America. American tugs are universally propeller boats, except on shallow rivers, where paddle-wheel steamboats sometimes are made to do the work of tugs. An American tug is a busy-looking boat. Her bow is fairly high, her deck slopes aft in a rather marked curve. Her stern is low. A deck house extends from the “towing bits,” or heavy built-in posts to which the towline is made fast, up to within ten or a dozen feet of the bow. This deck house is not high—hardly higher than a man’s head—and contains a galley and a mess room, besides entrances to the boiler and engine rooms. On top of this, at its forward end, is the wheel house, as high as the deck house on which it sits. Astern of the wheel house is a huge funnel for so small a boat, and astern of that sits a lifeboat, resting in its “chocks.” But the surprise comes if an inquisitive observer goes to a local shipyard and sees one of these small steamboats in a floating dock with her bulky underbody visible. What stands above the surface seems but little compared with what is below. She may draw eight or ten or more feet. Her body lines are very full, and at her stern is mounted a propeller that seems almost large enough for a good-sized freighter. And it is, for these boats have not only themselves to propel; they must meet incoming ships which are more or less helpless to direct their movements in such limited spaces as are available in a harbour. If the new arrival be small, one tug can readily place her beside her pier. If the ship be the _Majestic_ or the _Leviathan_, then a dozen or more tugs must push against her mighty side, or puff great clouds of steam as they strain at great hawsers before the giant is safely at her berth. Every harbour needs these little workers, and their work is important, but there are other ships whose work is of a different sort, and even more important. These are the dredges that keep a harbour’s channels open, or cut new ones or widen the ones already there. I have not the space in which to go into a description of these grubbers in the mud, but I can mention a few of their more salient points.