The necessary data by which the curves of the timbers are delineated then are, the perpendicular height from the keel, the main or principal breadth, and the top-timber breadth: for as a ship is much broader near the middle of her length than towards the ends, so she is broader in the middle of her height than above and below; and this latter difference of breadth is continued throughout every point of her length. The main breadth of each frame of timbers is therefore the ship’s breadth nearly in the middle of her height in that part: and the top-timber breadth is the line of her breadth near the upper ends of each timber. It has been already observed, that as both sides of a ship are alike, the artificers only draw one side, from which both sides of the ship are built: therefore the timbers abaft the midship frame are exhibited on one side of the plane of projection, and the timbers before it on the other. Plane of PROJECTION, Plate I. A. The keel. B C. The line which expresses the upper-edge of the keel, from which the height of each timber, and height of its different breadths are measured. B D and C E, perpendiculars raised on the line B C, to limit the ship’s extreme breadth and height amid-ships; or, in other words, to limit the breadth and height of the midship-frame. A F. A perpendicular erected from the middle of the keel to bisect the line of the ship’s breadth in two equal parts. F * 9. The half-breadth line of the aftmost top-timber; being the uppermost horizontal line in this figure. Note. The seven lines parallel to, and immediately under this, on the right side of the line A F, are all top-timber half-breadths, abaft the midship-frame; the lowest of which coincides with the horizontal line D E. The parallel horizontal lines nearly opposite to these, on the left side of the line A F, represent the top-timber half-breadths in the fore-body, or the half-breadths of the top-timbers before the midship-frame. G, H, I, Q, R, S, T. The radii of the breadth-sweeps abaft the midship-frame; those of the breadth-sweeps in the fore-body, or before the midship-frame, are directly opposite on the right side. ⊕ A ⊕. The midship-frame, from the extreme breadth downwards. 1, 2, 3, 4, 5, 6, 7, 8, 9. The out-lines of timbers abaft the midship-frame, in different parts of their height. _a_, _b_, _c_, _d_, _e_, _f_, _g_, _h_. The outlines of the timbers before the midship-frame, in different parts of their height, h being the foremost, or knucke-timber. K _i_. The wing-transom, whose ends rest upon the fashion-piece. L. The deck-transom, parallel to, and under the wing-transom. M N O. The lower-transoms, of which O k is the third and lowest, _m_ _k_ P. The dotted line, which expresses the figure of the fashion-piece, without being canted aft. P. The upper-part, or top-timber of the fashion-piece.