SHIPBUILDING.

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floats upon the stream, it is evident that her upper works will beseparated iron) the bottom by the surface of the water, which willaccordingly describe an imaginary horizontal line upon the bot-tom from the stem to the stern post. The most elevated of thoselines is termed the load-'.vater-line, which is supposed to be drawnby the surface of the water on the tipper part of the bottom, whenshe is sufficiently laden for a sea-voyage. For if we supposethis surface a rule, and thereby describe a corresponding blackline along the vessel’s bottom, that line will be distinguished uponthe bottom, which is white, and represent what is called the load-water-line. If the ship is lightened of any part of her lading, andpreserves the same difference in her draught of water at the twoends; or, what is the same thing, if she is lightened so as to pre-serve the same equilibrium of the keel with regard to the surfaceof the water, it is evident that she will rise higher out of the water,so that the black line already described will be elevated above it;and another black line may be delineated upon the bottom, closeto the surface of the water, which will exhibit a second water-lineparallel to the first, but nearer the keel in proportion to the num-ber of feet which the ship has risen. Thus by lightening a shipgradually, and at the same time preserving the direction of herkeel, or the angle which the keel makes with the surface of thewater, a variety of water-lines may be drawn parallel to eachother, and to the load-water-line. The ribands are likewise ofgreat utility in ship building; they are narrow and flexible planksplaced on the bottom at different heights, so as to form a sort ofmould for stationing the inferior timbers between the principalones. They differ from the water-lines, inasmuch as the latterhave only one curve, which is horizontal; whereas the ribands,besides their horizontal one, have a vertical curve. We shallnow describe the principal pieces of whicli a ship is composed,and explain the principal draughts used in the construction. Asthe several lines exhibited in the planes of elevation, projection,&c. will be rendered more intelligible by a previous account ofthose pieces, we shall begin with reciting their names, and givinga summary description of their uses and stations. They are most-ly represented in the order of their disposition in Plate CLXX.fig. )6, inscribed pieces of the hull. A, The pieces which com-'pose the keel, to be securely bolted together, and clinched. B,The stern-post, which is tenanted into the keel, and connected toit by a knee, G. It supports the rudder, and unites the sides ofthe ship abaft. C, The stem, which is composed of two piecesscarfed together: it is an arching piece of timber, into which theship’s sides are united forwards. D, The beams, which are usedto support the decks, and confine the sides to their proper dis-tance. E, The false post, which serves to augment the breadthof the stern-post; being also tenanted into the keel. F, The kneeswhich connect the beams t» the sides. G, The knee of the stern-post, which unites it to the knee. II, The apron , in two pieces:it is fayed on the inside of the stem, to support the scarf thereof;for which reason the scarf of the former must be at some distancefrom that of the latter. I, The stemson, in two pieces, to rein-force the scarf of the apron . K, The wing-transom : it is fayedacross the stem-post, and boltechto the head of it, having its twoends let into the fashion-pieces. L, The deck-transom, parallelto the wing-transom, and secured in the same manner. MN, Thelower transoms. O, The fashion-piece on one side; the heel ofit is connected with the dead wood, and the head is secured to thewing-transom. P, The top-timbers, or upper parts of the fashion-pieces. Q, 'Fhe knees, which fashion the transom to the ship’sside. R, The breast-hooks, in the hold; they are fayed acrossthe stem, to strengthen the forepart of the ship. S, The breast-hooks of the deck : they are placed immediately above the for-mer, and used for the same purposes. T, The rudder, which isjoined to the stern-post by hinges, and serves to direct the ship’scourse. U, The floor-timbers; they are laid across the keel, towhich they are firmly bolted. V, The lower futtocks, and, W,The top-limbers, which are all united to the floor-timbers, form-ing a frame that reaches from the keel to the top of the side. X,The pieces which compose the kelson ; they are scored about aninch and a half, as exhibited by the notches. Y, The severalpieces of the knee of the head; the lower part of which is fayed tothe stem ; the heel being scarfed to the fore-foot. Z, The cheeksof the head or knees, which connect the head to the bows on eachside. &, 1 he standard of the head, which fastens it to the stem.a, The cat-heads, one of which lies on each bow, projecting out-

wards like the arm of a crane. They are used to draw the anchor,up to the top of the side without injuring the bow. b, The bitsto whicli the cable is fastened when the ships rides at anchor, c,

I The false post, in two pieces, layed to the fore part of the stern-j post. d, The side counter-timbers, which terminate the ship; abaft within the quarter-gallery, e, e, Two pieces of dead wood,one afore and another abaft, fayed on the keel. In vessels of war,the general dimensions are established by authority of officers ap-pointed by the government to superintend the building of ships.In the merchant-service, the extreme breadth, length of the keel,depth in the hold, height between decks and in the waste, areagreed on by contract; and from these dimensions the shipwrightis to form a draught suitable to the trade for which the ship is de-signed. In projecting the draught of a vessel of war, the first ar-ticle to he considered is her length. As all ships are much longerabove than below, it is also necessary to distinguish the precisepart of her height from which her length is taken : this is usuallythe lower gun-deck, or the load-water-line. Water-lines are de-scribed longitudinally on a ship’s bottom by the surface of thewater in which she floats, and that the line which determines herdepth under the water is usually termed the load-water-line. Inthis draught it is particularly necessary to leave sufficient distancebetween the ports. The next object is to establish the breadth bythe midship-beam. Although there is great difference of opinionabout proportioning the breadth to the length, yet it is most com-mon to conform to the dimensions of ships of the same rate.After the dimensions of the breadth and length are determined,the depth of the hold must be fixed, whicli is generally half thebreadth; but the form of the body should be considered on thisoccasion ; for a flat floor will require less depth in the hold thana sharp one. The distance between the decks must also be settled.We may then proceed to fix the length of the keel, by which we shallbe enabled to judge of the rake of the stem and stern-post. The rakeis known to be the projection of the ship at the height of the stern andstern-post beyond the ends of the keel afore and abaft, or the an-gle by which the length is increased as the fabric rises. To thesewe may also add the height of the stem and wing-transom. Afterthese dimensions are settled, the timbers may lie considered whichform the sides of the ship. A frame of timbers, whicli appears tobe one continued piece, is composed of one floor-timber, U,whose arms branch outward to both sides of the ship; two or threetuttocks, V V ; and a top-timber, W. The futtocks are connect-ed to the upper arms of the floor-timbers on each side of the ship,and serve to prolong the timber in a vertical direction: and thetop-timbers are placed at the upper part of the futtocks for thesame purpose. All these being united and secured by cross-bars,or a circular inclosure, which is called a frame of timbers. Andas a ship is much broader at the middle than at the extremities,the arms at the floor-timber will form a very obtuse angle at theextreme breadth : but this angle decreases in proportion to thedistance of the timbers from the midship-frame, so that the fore-most and aflmost ones will form a very acute angle. Floor-tim-bers of the latter sort are usually called crutches. Shipwrightsdiffer extremely in determining the station of the midship-frame ;some placing it at the middle of the ship’s length, and other fur-ther forward. They who place it before the middle allege, thatif a ship is full forwards, she will meet with no resistance after shehas opened a column of water; and that the water so displacedwill easily unite abaft, and by that means force the ship forward ;besides having more power on the rudder, in proportion to its dis-tance from the centre of gravity ; this also comes nearer the formof fishes, which should seem the most advantageous for dividingthe fluid. When the rising of the midship-floor-tiniber is deci-ded we may then proceed to describe the rising-line of the floor ,on the stern-post abaft, and on tbe stem afore. We come now toconsider the upper works, and all that is above water, called thedead work: and here the ship must be narrower, so that all thaweight lying above the load-water-line will thereby be broughtnearer the middle of the breadth, and of course the ship will beless strained by the working of her guns, &c. But although someadvantages are acquired by diminishing tile breadth, above water,we must be careful not to narrow her too much ; as there must besufficient room left on the upper deck for the guns to recoil. Thesecurity of the masts should likewise be remembered, which re-quires sufficient breadth to spread the shrouds. A deficiency ofi this sort may indeed be in some measure supplied by enlarging