The keel is laid down on blocks, four or five feet apart, which form a slope toward the water, so that the hull may glide down easily when the time for launching comes. It is not a keel at all, in the sense in which the word was formerly used: a modern ship has a smooth bottom, without any projecting ridge or break to the curve of her sides; it is simply the central series of plates, from which an inner keel is built up like an enormous backbone, and to this the ribs are attached. The metal is delivered at the yard in the shape of angle iron or angle steel, the latter being the material which would be used in a ship of the class we have in mind. Heated to a white heat, the angle-bars are drawn out of the furnace into a perfectly level iron floor, upon which they are bent to the needed curve, and that which has been a line of ink in the original drawing, a chalk mark on the floor of the mould loft, and a groove in the surface of the “scrive board,” is now embodied in the heavy rib of the ship. The bending is done thus: the metal floor is perforated with thousands of holes, into which iron pegs are inserted until they form the curvature required, and the long, pliable bar of steel is pressed against them until it corresponds exactly with the line exhibited in the “scrive board,” which is always in sight of the workmen for guidance and comparison. In handling the metal the men use pitchforks, and with the prongs inserted in the holes they get purchase enough to make the bar yield; if it bends upward a hammer is used upon it. Each rib has, of course, to be duplicated with the utmost precision, in order that it shall be the same on both sides of the ship, and each, after it has cooled, is laid upon the “scrive board” and compared with the lines thereon, every variation being corrected before it is passed. Having already been punched for rivets, it is then marked with a chisel to show where rib-bands, stringers, and deck-beams are to fit into it. Two or three months or less after the completion of the “fairing,” the ship is probably “in frame,” and looks like the skeleton of some Brobdignagian monster that has stranded on the bank of the river. The ribs have been hoisted into position at right angles with the keel, and strung together by “rib-bands,” and already there are signs of the coming subdivision by decks and bulkheads of the hollow space within. You can still see through her, however; she is like, to make yet another comparison, a great oblong wicker-basket, the supple willows being represented by the net-work of steel.