A. longitudinal layer or course of planks is then fastened to the moulds all round ; namely, bottom, sides, and deck; sheets of tarred paper are then laid en, and a second course of planks is put upon the course, athwart, all round the first course, as shown in the subjoined figure, which crosses the grain of the wood, and moat essentially contributes to the strength of the fabric ; each course or plants is tree-nailed together, and the courses continued in alternate dim dons till a sufficient substance is acquired for the dtrength of the vessel. The keel, stem, and sterrf-posts, are put on with the last course, as shown in Fig. 4, and then the whole are tree-nailed through and through, each tree-nail being driven hard in, then split at the end and wedged. .The dead wood fore and aft is formed by cross planking, to fill up the space between the body of the vessel and the stern and stern-posts. To save the bottom, strengthen it, and keep the • vessel upright when aground, two bilge keels are tree-nailed or bolted through into bile planks in the inside of the vessel ; stanchions, with brackets, are fixed to the sides and deck, and the bulwarks are formed prior to the last course of, planking ; the last course is then laid to finish the deck : the hatchway and; companions are then cut out of the solid deck, and the conlynd intrWuced. This system of building is said to require much less timber, being without knees, beams, and ribs, and is, therefore, more buoyant—causes no loss of time in building, for seasoning the timber—avoids the dry rot, from air and moisture being excluded from the inner courses—the resistance more elastic, and pre senting, in every direction, an arch to sustain external shocks ; and, it is added, that in case of warfare, the destructive effects arising from splinters will be entirely avoided.
A curious mode of defending ships against the effects of cannon balls, was proposed by the intelligent and philanthropic Lewis Gompertz, Esq., of Ken nington Oval, and was published in the scientific journals a few years ago •, a condensed account of which we insert, conceiving it to be not altogether unde serving of the attention of the scientific reader. The chief utility promised by the invention, is in its application to merchant vessels, ships of passage, &c., and for fortifications; but for ships of war (as it could be adopted by both par ties), its effect would become neutralized, though it seems that even in this case it would save the men from injury, and would always be in favour of the weak and defensive side—its nature being that of defending itself, and returning the blows, but without any power of attacking, unless furnished with guns also.
The annexed figure gives a transverse section of a ship, with its sides con structed with oblique and curved surfaces, so as to cause the balls projected against it to glance off at an angle, which angle, supposing the surfaces of the bodies in collision to be elastic, will be always equal to that formed by the line in which the projectile moves, and that.of the surface it strikes; that is to say,
according to the well-known law of the angle of reflection being always equal to the angle of. incidence. If, therefore, a'shot strikes the upper side of the beveled part a, it will be reflected at a similar angle, and be thrown over the vessel; and if it strikes the lower side of b it will be reflected at a similar angle, into the water, as shown by the balls and the direction of the arrows: but if a ball strikesagainst the inclined plane of the triangular-formed piece projecting between a and b, it will rebound at nearly equal angles from side to side; then, inking the curve, it will be returned to the point from whence it was projected.
As the force of the balls thus returned would be so much diminished as to have • probably little effect upon the enemy, it might be advisable to dispense with the curved part, and make the whole defence consist of one angular projection, pre senting two inclined planes only. The grain of the wood in these projections should be in the direction of the motion of the balls, and not transverse ; and a coating of grease on the external surface would assist in warding off the inju rious effects of the shot.
Mr. E. Carey, of Bristol, who has bad much experience in ship-building, and has suggested a variety of improvements, recommends the following method of fastening a ship's side, with his newly-invented iron knees, as explai•ied by the subjoined figures. Fig. 1 is a horizontal section of a portion of a ship's side and beams ; AA shows the ship's side ; B B the timbers ; C C the thickness of the outside planking; D D a plank, 34 inches thick, which goes all round the ship, inside the timbers, against which the iron knees are fixed, and bolted through the side; e e an horizontal clamp, 10 inches wide and 6 inches thick ; F F the iron knees, 4 inches wide and 2 inches thick, which ate bolted through the beams and ship's side, as at G G. Fig. 2 is a section-of the same parts as Fig. I. H is the plank sheer; I the water way ; J J the ends of the planks ; K a bolt that goes through the ship's side, through the edge of the water way, and six streaks of the deck below the beam, and is clenched on an iron plate on the inner plank ; L the arm of the knee ; M the ship's timber and side; D is an edge-view of the inner plank, as shown at D, Fg. 1. These iron knees and water ways are let down upon the beam 3 inches, and also six of the deck planks, and bolted through also; under the beam a plank, 34 inches thick, is first brought on, inside the ship, against which the ends of the beam are fixed. The horizontal clamp, 10 inches wide and 6 inches thick, is then brought on under the edge of the plank, and bolted through the side. On this clamp the beam is dovetailed in, one inch down, and bolted through the end of the beam. A ship fastened in this way, Mr. Carey says, will render it impossible for the side to move ; that no wet can possibly get down, and that the ship will thus be kept perfectly dry and sound. .