SHIPBUILDING.

577

the breadth cf the channels. In the sheer-draught, or plane ofelevation of a sixty gun ship, (fig. 2, Plate CLXVlll.) the sameletters refer to the same objects, as in the explanation of thepieces, as above; at least when the same objects are in bothfigures. AA, is the keel, whose upper edge is prolonged by thedotted line pg, upon the extremities of which are erected perpen-diculars which determine the height of the wing-transom K, andthe whole length of the gun-deck KC. AB, the stern-post. AC,the stem. DD, the quarter-gallery with its windows. EF, thequarter-pieces, which limit the stern on each side. F, the taffarel,or upper piece of the stern. FG, profile of the stern, with itsgalleries. A, the gun-ports. I, the channels, with their dead-eyes and chain-plates. K, the wing-transom. KG , the counter.LB, the deck-transom. MNO, the first, second, and third tran-soms, of which Ok is the third or lowest. wiOLP, the directionof the fashion-piece, having its breadth canted aft towards thestern. QR, the main-skeeds, for hoisting in the boats clear of theship’s side. LQZ, the main wale, with its sheer afore andabaft. DRX, the ■ channel-wales, parallel to the main wale.SUS, the sheer-rail parallel to the wales. Tf, the rudder.AtF, the, rake of the stern. VWV, the waist-rail. P ii, thedrift-rail abaft; and the drift-rails forwards. TUC the water line;XX, and fa the rails of the bead. Y, the knee of the head, orcutwater. ZZ, the cheeks of the head, aa, the cat-head.M©C, the rising line of the floor. kuC, the cutting down line,which limits the thickness of all the floor-limbers, and likewise theheight of the dead wood afore and abaft. ©itUW, the midship-frame. a, b, c, d, e, f, g, A, the frames or timbers in the forebody of the ship, i. e. before the midship-frame. 1, 2, 3, 4, 5, 6,7, 8, 9, the timbers in the after body, or which are erected abaftthe midship-frame. As the eye of a spectator is suppossed in thisprojection to view the ship’s side in a line perpendicular to theplane of elevation, it is evident that the convexity will vanish,like that of a cylinder or globe, when viewed at a considerabledistance; and that the frames will consequently be representedhy straight lines, except the fashion-piece abaft and the knuckle-timber forward. The plane of projection' may be defined hy a■Vertical delineation of the curves of the timbers upon the plane ofthe midship-frame, which is perpendicular to that of the elevation.R he various methods by which these curves are described, are®qua!ly mechanical and arbitrary. In the latter sense, they arecalculated to make a ship fuller or narrower, according to theservice for which she is designed ; and in the former they aredrawn according to those rules which the artist has been implicitlytaught to follow, or which his fancy or judgment has esteemedthe most accurate and convenient. They are generally composedseveral arches of a circle, reconciled together by moulds framed‘°r that purpose.

Or THE Plane of-Projection.

Plate CLXX. fig. 17. A, is the keel. BC, the line whichexpresses the upper edge of the keel, from which the height of each'tuber and height of its different breadths are measured. BD, andl perpendiculars raised on the line BC, to limit the ship’s ex-r eme breadth and height amid-ships; or, In other words, to limitbreadth and height of the midship-frame. AF, a perpendi-ular erected from the middle of the keel to bisect the line of thefi’p’s breadth in two equal parts. F 9, the half-breadth-line of^ e aftmost top-timber; being the uppermost horizontal line in thisSure. The seven lines parallel to, and immediately under, thisab fti r 'S* lt8 'de of the line AF, are all top-timber-half-breadths,P ” the midship-frame; the lowest'of which coincides with thet --°"ta, line DE. The parallel horizontal lines nearly oppositehalf i 6 ’ 011 t ' 1e siclu of the line AF, represent the top-timberb P ”, ai Bhs ’ n l * le f° re Body, or the half-breadths of the tdp-tim-Before the midship-frame. G, H, l, Q, R, S, T, the radii ofSw re adth-iweeps abaft the midship-frame ; those of the breadthoon ^ 1 ' le fore-body, or before .the midship-frame, are directly

the ° S ' te 011 l * le r, S ht s 'de. © A shew the midship-frame, fromoutlit} X - treme Breadth downwards. 1,2, 3, 4, 5, 6, 7, 8, 9, theof.i of the timbers abaft the midship-frame, in different partsBefore"')! IR B ( . c > G c ’ f- S' G the outlines of the limbers

the f 0 - ' e "Bdsliip-frame, in dilleivnt parts their height, A beingends _ iemost or knuckle-timber. K ?, the wing-transom, whoseVo, eS , U|>0 » f' le fashion-piece. L, the deck-transom, parallel' tv.— no. 196.

to and under the wing-transom. MNO, the lower transom, ofwhich Ok is (lie third and lowest. wi/cP, the dolled line, whichexpresses the figure of the fashion-piece, without being canted aft.P, the upper part, or top timber of the fashion-piece, n, o, p, q,r, s, the radii of the floor-sweeps, abaft the midship-frame ; thosebefore the midship-frame aie on the opposite side of the line AF, towhich they are all parallel. 1 st R d , 2d R d ,3 d , R d , 4thR d , the diagonalribands abaft the midships t, u, x, y. The same ribands expressedin the fore body. The horizontal plane is composed of water-lines and ribands; it also contains the main and top-timber-breadth lines, on the longitudinal lines by which the main breadthand. top-timber-breadth are limited in every point of the ship’slength. The horizontal curve of the transoms and harpins are alsorepresented therein ; together with the planes of the principal tim-bers, the cant of the fashion-piece, the length of the rake atore andabaft, the projection of the cat-heads, and the curve of the upperrail of the head, to which the curves of the lower ones are usuallyparallel.

Of the Horizontal Plane.

BAG, Plate CLXVIII. fig. 3, the line of the ship’s length pass-ing through the middle of the stem and stern post. C, the upperend of the stem. BF, the length of the rake abaft. 13WX, thetop-timber-breadth of each top-timber. DF, the breadth of theaftmost timber at the tafliel. BK, the wing-transom. BLP, thehorizontal curve of the deck-transom. MM, the horizontal curve,or round aft, of the first transom. MN, the horizontal curve ofthe second transom: it is prolonged into a water-line, N 8, 7.AO, the horizontal curve or the third transom, which is also pro-longed into another water-line, O, n, U, p, Q. wOP, the plane ofthe fashion-piece, as canted aft. ©WU, the plane of the midship-frame a, b, c, d, e, f, It, the planes of the timbers before, the mid-ship-frame. 1, 2, 3, 4, 5, 6, 7, 8, 9, the planes of the timbersabaft the midship-frame. XX, the figure of the upper rail of thehead. CY, the projection of the knee of the head. The thirdhorizontal riband is marked on the plate, a a, the projection ofthe cat-head. Thus vve have endeavoured briefly to explain thenature and uses of the principal draughts used in the constructionof a ship, which reciprocally correspond with each other in the di-mensions of length, breadth, and depth. Thus the plane-of ele-vation is exactly of the same length with the horizontal or floor-plane. The several breadths of the timbers in the floor-plane, andthat, of the projection exactly conforms to their height in the ele-vation. Thus, let it be required to transfer the height of the wing-trainsom from the elevation to the projection: extend the com-passes from the point K, in the elevation, down to the dotted lineprolonged from the upper-edge of the keel, and setting' the otherroot in the point p, Chen shall the line K p be the perpendicularheight in the wing-transom: transfer this from the middle of thelines BAC , in the projection to the point K in the perpendicularAF, then will AK be. the height of the wing-transom in the planeof projection : and thus the height of all the transoms may be laidfrom the former upon the latter. Again ; let it be required totransfer the main breadth of the midship-frame from the projectionto the horizontal plane ; set one foot of the compasses in the point© on the perpendicular CE, and extend the other along the main-breadth-sweep © G, till it touches the perpendicular AF parallelto CE: lay this distance upon the horizontal plane from the pointu m the line of the ship’s length, BAC , along the plane of themidship-frame to the point ©; so shall the line © WU he thebreadth of the midship-frame on the horizontal plane. Thus alsothe top-timber-breadth, or the distance of each top-timber fromthe middle of the ship’s breadth, may be in the same mannertransferred, by extending the compasses from the line BAC , inthe horizontal plane, to the top-timber-breadth-line, upon anyparticular timber, as 1, 2, 3, &c. which will give its proper di-mensions thereon. In the same manner the breadths of all thetimbers may be laid from the projection to the horizontal plane,and vice versa, from that to the projection. Thus, the height ofeach timber may also be transferred from the elevation to theprojection, &c. The principal utility of these draughts, there,-fore, is to exhibit the various curves of the ship’s body, and ofthe pieces of which it is framed, in different points of view, whichare either transverse or longitudinal, and will accordingly presentthem in very different directions.

7 H

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