The plank of the bottom is fastened by one cop per bolt in each butt, and by one treenail in each timber, and it receives additional security by the bolts passing through it which connect the diagonal frame, and of which we are about to speak. This trussed frame is composed of diagonal timbers. (or braces, Plate CCCCXCVIII. Fig. 1. B.) of horizontal pieces (C) and of trusses (D.) The diagonal timbers are first put in place, and lie at an angle of 45° with the timbers of the frame; they are coaked and bolted to those timbers as well as to the clamps over which they pass. The longitudinal pieces are then put in place, and finally the diagonal trusses; thus the whole combination forms a series of triangles. In the fore body, the keels of the diagonal timbers meet, and being connected with straps of iron, form breast hooks—those in the after body arc united in the same manner and form crutches—accuracy of workmanship is highly desirable in the frame, as the closer the horizontal pieces and trusses are in contact with the braces, the less will be the alteration in the figure of the ship from arching or hogging.
Two additional keelsons arc worked in midships, (Plate CCCCXCVI1I. Fig. S. H) one. on each side; these extend about 33 feet and are placed at such a distance from the regular keelson, that the ends of the step of the mainmast may rest upon them, and by being coaked or bolted to the floors or cross pieces over which they pass, strengthen the ship iu that part, and prevent alteration in form by the weight and stress of the mast downwards, or by the pressure of the wa ter upwards, on those floors which lie in nearly a hor izontal position.
The gun deck clamps and shelfpiece are got in place, the beams coaked and bolted thereto. the spir ketting and •aterings worked, and the chock placed under the shelfpiece; the beams of the gun deck are fastened by a forked knee, (Plate CCCCLXXXVIII. Fig. 5.) The description which has been given will be suffi cient to show in general terms the progression made in building ships, as it would be unnecessary to dilate upon a progress nearly similar through the several decks; suffice it to say, that the outside planking pro ceeds progressively with the inside. \Ve shall pro ceed to give the methods of putting together and fas tening the several parts.
Brains of the principal from their great length and size, are usually made in three pie ces, the tops of the trees which make the two end pie ces abut, and the deficiency of their scantling in the middle of the beam, is compensated by a middle piece which is coaked and bolted to the two end pieces.
Shelf pieces,—(Plate CCCCXCV111. Fig. 1. a,) are coaked and bolted to the clamps and to the beams of the several decks; they may be considered as internal hoops, and by connecting the frame and beams pre serve the form of the ship.
Chocks under shelf CCCCXCVIII. Fig. 3. c.) Where the beams do not come directly over the ports, chocks are placed under the shclfpiece and immediately under the beams. Upon the chocks, the face of the iron clasp knee rests, and is bolted. Where the beams do come over the ports, they are attached to the ship by an iron hanging knee, fasten ed against the side at a sufficient angle of inclination to clear the ports.
Trussing between the ports. of all the planks between the ports being laid in a horizontal position, a diagonal truss, (Plate CCCCXCVIII.
1. C,) is placed against abutment pieces (F) between each port to prevent the arching of the ship. The trusses (in midship) at the neutral axis are double (G.) Waterways, (Plate CCCCXCVI II. Fig. 3, d,)— These are rounded in front, are scored down on, and coaked and bolted to the beams; a rabbet is taken out on the fore side to receive the planking of the diagonal decks; this is sufficient depth to give a seam of 3 in ches for caulking.
beams and half beams for the recep tion of the plank of the decks are so placed as to give the greatest degree of strength, but so disposed as to leave such openings as may be necessary for the hatchways, ladderways, rooms for capstans, &c.; the planking of the principal decks is then laid upon them in a diagonal direction, (Plate CCCCXCVIII. Fig 2;) the outer ends of the diagonal planking are received in the rabbet cut in the waterways, the inner ends abut against thick strokes running in a fore and aft direction in midships.
ships of the line and frigates are now built with circular sterns; the disposition of the tim bers is shown, Plate CCCCXCVIII. Fig. 4, and the galleries in Plate CCCCNCIX. Fig. 1.
The foregoing observations have been chiefly con fined to the building of ships of the line. The differ ence in frigates is, that instead of working in the hold a diagonal framing. of wood, iron trusses are laid on the timbers at an angle of 45', and at a distance of 6 feet from each other; and over the joints of the tim bers, and crossing these trusses, two strokes of thick plank are worked, Plate CCCCXCVIII. Fig. 7.
In sloops and smaller vessels their bottoms are also made solid as high as the line of water, and a thick stroke placed over the joints of the timbers in the hold. The beams are not in general kneed, but fas tened by being coaked and bolted only to the water ways and shelf pieces; two or three iron knees, how ever, are usually placed under those beams on each side, which are nearly opposite to the mainmast, and the same number to those similarly situated with respect to the foremast.