For the first day, while the steel decks are being scrubbed so clean that one might lie upon them without soiling himself, the passengers may spend every hour in exploring the mysteries of the ship without finding a dull moment. Under the aft deck-houses, where the crew eat and sleep, are what the sailors call the “bowels of the ship,” and here, as is not the case on ocean craft, the passenger may see for the first time in his life the wonderful, almost appalling, mechanism that drives a great ship from port to port, for it must be remembered that the “passenger” here is a guest--the guest of the owner whose great private yacht the great ship is, in a way, and everything of interest will be shown to him if he wishes. Of the bottom of this part of the ship the “brussels-carpet guest”--as sailors call the passenger who is taking a trip on a freighter for the first time--stands half in terror. There is the dim light of electricity down here, the roaring of the furnaces, the creaking and groaning of the great ship, and high above one’s head, an interminable distance away it seems, one may see where day begins. Everywhere there is the rumbling and crashing of machinery, the dizzy whirling of wheels, the ceaseless pumping of steel arms as big around as trees; and up and up and all around there wind narrow stairways and gratings, on which men creep and climb to guard this heart action of the ship’s life. The din is fearful, the heat in the furnace-room insufferable, and when once each half-minute a furnace door is opened for fresh fuel, and writhing torrents of fire and light illumine the gloomy depths, the tenderfoot passenger looks up nervously to where his eyes catch glimpses of light and freedom far above him. And then, in the explanation of all this--in the _reason_ for these hundreds of tons of whirling, crashing, thundering steel--there comes the greatest surprise of all. For all of this giant mechanism is to perform just one thing--and that is to whirl and whirl and whirl an insignificant-looking steel rod, which is called a shaft, and at the end of which, in the sea behind the ship, is the screw--a thing so small that one stands in amazement, half doubting that this is the instrument which sends a ten-thousand-ton ship and ten thousand tons of cargo through the sea at twelve miles an hour!