"The third is the body plan, and exhibits a vertical section of the hull, looking at it end-on, at the point where it has the greatest breadth. The right-hand half of it shows the bows, and the left the stern. The curved lines are the same as those on the sheer plan, though, of course, they are shown only at the bow and stern, for you cannot see a line when you look end-on. "With the making of these plans the task of the naval architect comes to an end, unless he is employed to superintend the construction of the vessel. From the plans the builder gets the exact size and shape of the craft he is to build. From it the moulds, or patterns, of all parts of the hull are made. In an apartment called the moulding-room, with which every ship-yard is provided, full-sized plans of the vessel are drawn on the floor. I do not mean that the entire ship is drawn at the same time. "If the bow or stern was accurately transferred to the floor, enlarged to the actual size of the hull, the exact form of the stem or stern post could be marked off. From this, a mould or pattern could be made of board or plank. As a matter of fact, a mould is made for every part used in the construction of the ship, not every piece of wood, for what is used for one side may do just as well for the other side. For example, a timber on one side is exactly like the one on the opposite side. "In ship-building, the word timber has two meanings. As in general use, it may be any large stick of wood. In the technical sense, it is one of the ribs of the vessel. The means of understanding which is meant will be given you as you proceed with the work. The keel is the backbone of the vessel, and the strength of the hull depends largely upon it. "The keel corresponds with the backbone of your bodies. At the forward end of it is the stem, shaped as you see in the sheer plan. At the after end is the stern-post; and these three parts form the profile of the vessel. Between them are the timbers, or ribs, curved as required by the shape of the hull. To the timbers, the stem and stern-post, the planking, or outer skin of the ship, is fastened. If you were to build a canvas canoe, you would make a frame such as I have described. The cloth part would correspond to the planking. "But, besides the principal parts I have mentioned, of course there is a vast number of other parts, whose names you could not remember if I gave them to you. I shall add only a few of the principal ones. The timbers--I use the word in its technical sense--are set up about three feet apart, sometimes a little more, and sometimes a little less. The lower end of each is fastened to the keel, and of course each timber has to be shored up, and carefully secured in its proper position.