On Naval Timber and Arboriculture. Patrick Matthew
in the ratio of the cube root of the tonnage—a little deeper and thicker in the smaller vessels. When timbers are formed of larch or pine, they require to be a little more in diameter than when of oak. {18}
Fig. a, Flat floor, from 9 1⁄2 to 18 feet long (that is, 9 1⁄2 for a vessel of 50 tons, and 18 for one of 500), and from 9 to 16 inches deep at middle; thickness 1⁄4th less than depth, the diameter increasing in proportion to the length. When fillings such as s are used, flat floors are cut from straight logs.
b, Rising floor shorter, and same depth and thickness as former.
c, c, High rising floors, from 4 to 8 feet in length of wing, and a little deeper, and same thickness as former. From the difficulty of procuring this bend, the wings are often used of unequal length, according as the timber turns out, the shorter wing to exceed 3 feet, and more when of considerable diameter. Floors are of every rise from a to c, being flattest at midships, and rising gradually as they approach the bow and stern. In all timbers, it is necessary, for strength, that the fibre of the wood extend from one end to the other without much cross grain. See lines on high rising floor, c.
d, First foot-hook, from 7 to 13 feet long, and from 7 to 14 inches deep; thickness 1⁄5th less than depth.
e, Second foot-hook, from 6 to 10 feet long, and from 6 to 13 inches deep, thickness 1⁄6th less than depth. This curve, when of great size, is valuable as, breast-hooks—curved timbers stretching horizontally within and at right angles to the bow-timbers, to support the bow.
f, f, f, Knees, the one wing nearly at right angles to the other; from 2 to 9 feet in length of wing; depth at middle as much as possible; thickness from 4 to 12 inches—generally required about 3 1⁄2 feet in length of wing, and from 6 to 8 inches thick. Knees, when large, suit for high rising floors.
Fig. h is a valuable piece, and easily procured by bending the young plant; when cut, it forms two second foot-hooks.
Figs. a, b, c, d, e, are suitable, though the part cut off by the dotted line be awanting. In good work, this plan is often followed, and a cross-chock put on. (Vid. s, left side of the cross-section of a vessel thus timbered, page 20). By this {19} mode of building, vessels can be constructed from much straighter timber, and the vessels are superior, from being more elastic; but from the nicety and expense of the work and waste of timber, the practice is not much in use.
Cross-section of a Vessel at midships—knees not inserted.
A first foot-hook alternates with each floor, and second foot-hook, alongside, extending from o to q; and a top-timber, or third foot-hook, alternates alongside of each second foot-hook, and chock extending from q to a. These timbers are bolted together, and constitute a frame or double rib; and the skeleton is composed of a series of double ribs (several inches separate, of course wider above than lower down, as the timbers decrease in thickness), to within a little of the bow and stern, where the timbers are usually placed singly, without framing. {21} In large vessels a fourth futtock is used; thence straighter timber is suitable.
The knees occupy the position at x, stretching horizontally along the inside of the vessel and end of the beams.
Of British trees, timbers are formed of oak, Spanish chestnut, larch, red-wood pine, red-wood willow (the stags-head ozier, Salix fragilis), and sometimes the broad-leafed elm (Ulmus montana) under water.
In Britain, crooked oak for timbers is found chiefly in hedge-rows and open forests, where the winds, casual injury, or overhanging superior branches, have thrown the tree, while young, from its natural balance; or, by the tree, from open situation, or excision of lower branches, parting early into several leaders, which, in receding from each other, form curves and angular bends. On the Continent of Europe, in the natural forest, it is chiefly the tops of old lofty trees which afford the crooks; in consequence, those we import are, for the most part, of a free, light, insufficient quality9. {22}
To procure a sufficiency of excellent crooks, every person who has the charge of young plantations of timber intended for naval purposes, ought, in the more exposed situations not favourable to the growth of plank timber, or timber for bending, when the plants are from 3 to 15 feet high, to mark out the most healthy, suitably formed plants, sufficiently close to fill the ground when of the proper size, say 6 yards apart, and to bend these, as the under figures will illustrate. The dotted portion is the growth after being bent. {23}
The bend of floors requiring to be at the middle, and of angular bend, see Fig. f, young trees of one-half the required length, should have the earth removed from the bulb of the root, from one or both sides, according to circumstances, and the tree and stool partially upset to windward, that is, generally south-west; (the operator, in effecting this, may be assisted by a strong pronged instrument); then fixed in this inclined position, and the earth filled in. This inclination may be given at planting, when the plants are tall.
The best mode of securing the larger plants in their bent position, is by rods, forked or hooked at one end, the other end nailed to a ground-stake;—the upper end, if forked, firmly tied to the bent plant by mat or straw rope. Smaller plants may be secured to the notched tops of stakes by ligatures; and the smallest, particularly larch, pinned down by small stakes with hooked tops. Advantage may also be taken of an adjacent tree of small value, and which would ultimately be required to be thinned out, to tie the bended standard down to the most convenient part of its top or stem, lopping off all above the ligature, if it interfere with the standard, and barking it near the ground, to prevent much future growth. When the workmen comprehend {24} the required bends, they will fall upon methods of fixing the plants in the most suitable position, better adapted to the locality than any directions can teach. The plants will require to be fixed down at least two years, and bent a little more than what is requisite, as in their after-growth they have generally a tendency to become straighter, from depositing the thickest layers in the hollow of the bend. A fine regular curve may be obtained by bending the plant for several successive years, a little lower every year; this gradual lowering does not so much check the growth of the leader, nor tend so much to cause the feeders upon the upper side to push as leaders. When oaks are bent, great attention must be paid to cut away any ground-shoots, and to cut off or twist down any strong feeders that stand perpendicular on the upper side of the tree; and also for several years afterwards, to look over the trees twice a-year, correcting any exuberant feeder, and destroying root-shoots. The forester ought to keep in mind that his pupils are proverbially pliant, and that, should his growing timber not be of the most valuable and most appropriate figure, he must rank either with the negligent or the incapable.
Ship timbers being generally required of greater depth than thickness, that is, broadest in the plane {25} of the curve, hedge-row is better adapted to growing them than the forest, especially when the trees are close in the row. The bend generally takes place across the row; and the bole of the tree acquires a greater diameter in that direction than in the line of the row. If the figure of the top of a tree be very elliptical in the horizontal plane, the cross section of the bole, instead of being circular, will also be elliptical (cake-grown). The lateral spread of the roots in thick planted rows being greater than the longitudinal, also tends to give elliptic bole, the stem swelling most on the sides where the strongest roots enter, which, of course, always occurs on the sides affording most nourishment. Forests intended for ship timbers might be planted and kept in rows a considerable