MAST HOUSE.
The masts of a “ship” are three in number, a “schooner” has two, and a “sloop” but one. These masts pass right down through the decks, and rest upon the keelson. In small vessels each division is made of one piece, but in larger ships they are made up of a central piece, with others fastened round it so as to enlarge and strengthen it. The first or lower division of the central mast is called the “main” mast, and that above it the “maintop” mast; the fore mast is divided into “fore” mast and “foretop” mast, and the after mast is called the “mizen” and “mizentop” mast, and the pieces above these the “foretop gallant” mast, “maintop gallant” mast, and “mizentop gallant” mast. These masts are made, and raised by cranes in a building called a mast-house, and placed in the right position in the ship floating beneath.
The outside of ships, as high as the “water-line,” is covered with a sheathing of copper to defend it from the action of the “worm” (Teredo navalis), which bores into and destroys the wood exposed to its ravages; the copper also presents a smooth surface to the water, and facilitates the motion of the vessel. At the stern of the ship is placed the “rudder,” a wooden construction turning like a door on fastenings, and which, by being moved on one side, presents a greater amount of resistance to the water, and consequently tends to turn the stern of the ship away from that side, thus altering its course. The decks of a ship are like the floors of a house, running across from side to side, and supported on strong beams bolted into the sides; they are slightly arched, to increase their strength, as they have in ships of war to support the weight of the guns, &c. A section of the decks and other parts of a ship is shown at [fig. 3]. where the general figure and the different parts described may be seen; the section is through the middle, from side to side. Most ships of any considerable size carry several boats with them, either on deck or suspended between the masts, to serve as a means of escape in case of fire, or any other accident requiring the crew to leave the ship, also as a means of keeping up communication with the shore. Ships of war are named according to the number of guns they carry, as a seventy-four, a hundred-and-twenty-gun ship, &c.
REPAIRING DOCK.
When ships have to be repaired they are brought into the repairing dock, which has a pair of gates shutting it off from the river; when they are closed (at low water) the water is pumped out from the dock, and the repairs done; when finished the water is let in, and the ship floats out. In small vessels it is sometimes sufficient to haul them on shore at high tide, so that when the tide is down they may be left high and dry and repaired, and when the tide is at the highest, hauled off again. Steam ships are constructed to be propelled either by paddle wheels having flat boards fixed to their circumferences, which on being turned round, take a great hold in the water, and so cause the motion of the ship; or by the screw-propeller, which has been described.
PADDLE AND SAILING SHIP.
BREAKING UP.