On Naval Timber and Arboriculture / With Critical Notes on Authors who have Recently Treated the Subject of Planting

by Patrick Matthew

The rot in larch taking place in the part appropriate to knees, the forester cannot be too wary in selecting the situations where there is no risk of its attack, for planting those destined for this purpose. It is also desirable, if possible, to have the knee timber in ground free of stones or gravel, as the grubbing in stoney ground is expensive, and the roots often embrace stones which, by the future swelling of the bulb, are completely imbedded and shut up in the wood, particularly in those places between the spurs {95} where the saw section has to divide them for knees. Were the roots carefully bared at an early period, it would tend to prevent the gravel from becoming imbedded in the bulb. Nothing can be more annoying to the shipwright, when he has bestowed his money, ingenuity, and labour, upon an unwieldy root, and brought his knees into figure at the cost of the destruction of his tools by the enveloped gravel, to discover stains of incipient rot which renders it lumber.

This plan of baring the roots might be extended to oak trees for knees, baring and pruning about a foot out from the bulb annually. By exposure to the air, the timber of the root would mature and become red wood of sufficient durability. When covered with earth, the root of the oak remains white or sap wood, and soon decays after being dug up, the matured wood of the stem scarcely extending at all underneath the surface of the ground. The roots of the pine tribe are the reverse of this, at least the bulb and the spurs near it, are the best matured, reddest, toughest, most resinous, part of the tree. It is probably unnecessary to observe, that it would be folly to remove the earth from the bulb of trees in situations where water would stand for any length of time in the excavation. {96}

Larch knees are possessed of such strength and durability, and are of such adaptation by their figure and toughness, that were a sufficient quantity in the market, and their qualities generally known, we believe that none else would be used for vessels of any description of timber—even for our war-navy of oak. In America, where it is difficult to procure good oak knees in their close forest, it is customary to use them of spruce roots even for their finest vessels. The knees of vessels have a number of strong bolts, generally of iron, passing through them to secure the beam-ends to the sides of the ship. Larch knees are the more suited for this, as they do not split in the driving of the bolts, and contain a resinous gum which prevents the oxidation of the iron.

As the larch, unlike the oak, affords few or no crooks naturally, excepting knees, the artificial formation of larch crooks is of the utmost consequence to the interest of the holders of larch plantations now growing. In order to obtain a good market for their straight timber, it is absolutely necessary to have a supply of crooks ready as soon as possible to work the straight up. This would increase the demand, and thence enhance the price of the straight more than any one not belonging to the craft could {97} believe. In good soil many of the crooks would be of sufficient size in twenty years to begin the supply, if properly thinned out. In a forest of larch containing many thousand loads, and which had been untouched by any builder, we have seen the greatest difficulty in procuring crooks for one small brig. It is only on very steep ground, and where the tree has been a little upset after planting, that any good crooks are found. From the rather greater diameter required of larch timbers, and also from the nature of the fibre of the wood, we should suppose that steam bending of larch timbers would scarcely be followed, even as a dernier ressort.

Larch, from its great lateral toughness, particularly the root, and from its lightness, seems better adapted for the construction of shot-proof vessels than any other timber; and opposed end-way to shot in a layer, arch fashion, several feet deep around a vessel, would sustain more battering than any other subject we are acquainted with, metal excepted. Were the part above water of a strong steam-vessel, having the paddles under cover, a section of a spheroid or half egg cut longitudinally, and covered all around with the root cuts of larch five or six feet deep with the hewn down bulb, external; well supported {98} inside, having nothing exposed outside of this arch, and only a few small holes for ventilators and eyes; there is no shot in present naval use that would have much impression upon it. Had such a vessel a great impelling power, and a very strong iron cutwater, or short beak wedge-shaped (in manner of the old Grecian galleys), projecting before the vessel under water, well supported within by beams radiating back in all directions, she might be wrought to split and sink a fleet of men-of-war lying becalmed, in a few hours. This could be done by running successively against each, midships, and on percussion immediately backing the engine, at same time spouting forth missiles, hot water, or sulphuric acid from the bow to obstruct boarding; but even though the external arch were covered with assailants like a swarm of bees, they would be harmless, or could be easily displaced. To prevent combustion by red hot shot, the larch blocks, after drying, might have their pores filled by pressure with alkali. However, the employment of bomb-cannon about to be introduced in naval warfare, throwing explosive shot, regulated with just sufficient force to penetrate without passing through the side of the opposed vessel, will render any other than metallic defensive cover ineffectual; but {99} this circumstance will, at the same time, completely revolutionize sea affairs, laying on the shelf our huge men-of-war, whose place will be occupied with numerous bomb-cannon boats, whose small size will render them difficult to be hit, and from which one single explosive shot taking effect low down in the large exposed side of a three decker will tear open a breach sufficient to sink her almost instantly. For the construction of these boats, larch, especially were a proportion bent, would be extremely suitable, and thence larch will probably, ere long, become our naval stay.

Larch has been used in the building-yards of the Tay for 20 years back; and there is now afloat several thousand tons of shipping constructed of it. The Athole Frigate built of it nearly 12 years ago, the Larch, a fine brig built by the Duke of Athole several years earlier, and many other vessels built more recently, prove that larch is as valuable for naval purposes as the most sanguine had anticipated. The first instance we have heard of British larch being used in this manner, was in a sloop repaired with it about 22 years back. The person to whom it had belonged, and who had sailed it himself, stated to us immediately after its loss, that this sloop had been built of oak about 36 years before; that at 18 years {100} old her upper timbers were so much decayed as to require renewal, which was done with larch; that 18 years after this repair this sloop went to pieces on the remains of the pier of Methel, Fifeshire, and the top timbers and second foot-hooks of larch were washed ashore as tough and sound as when first put into the vessel, not one spot of decay appearing, they having assumed the blue dark colour which some timber acquires in moist situations, when it may be stiled cured; being either no longer liable to the putrid change constituting dry rot, or which forms timber into a proper soil for the growth of dry rot; or, from this blueness caused by the union of the tannin with iron acting as a poison on vegetation: this blueness, resulting from some alteration in the balance of affinities, occurs chiefly in timber containing much of the tannin principle, in which larch abounds. The owner of a larch brig who had employed her for several years on tropical voyages, also assures us that the timber will wear well in any climate, and that he would prefer larch to any other kind of wood, especially for small vessels; he also states that the deck of this brig, composed of larch plank, stood the tropical heat well, and that it did not warp or shrink as was apprehended.

From the softness of the fibre and want of {101} density of the larch, we would not deem it suitable for planking vessels beyond the size of ordinary merchantmen, say 500 tons, as in the straining of very large vessels, when the greatest force comes upon the outward skin, the fabric of the wood might crush before it, along the edge of the plank, and throw (chew) the oakum. In ordinary sized vessels, however, larch plank retains the oakum better than oak, from greater lateral elasticity. For the purpose of timbers, if root-cuts[24], and properly bent, we would think larch suitable to the largest class of vessels; as, though light, it is tough and quite free from knot, crack, or cross-grain, which is so common in oak, and which occasions dense old oak in large masses to give way at once, before a shock or strain, the hardness and unyielding nature of the fibre concentrating the whole dirupting impetus to one point. Larch may also be advantageously employed in the ceiling or inside skin of the part of war vessels above water: shot bores it, comparatively, like an auger,—thence the structure will endure longer under fire, and life be much economized.

In all places where larch has become known, it has completely superseded other timber for {102} clinker-built boats, surpassing all others in strength, lightness, and durability. For this purpose, young trees of about 9 inches diameter, in root-cuts from 10 to 20 feet in length, with a gentle bend at one end, such as the larch often receives from the south-west wind, are the most suitable. The log should be kept in the bark till used, and in dry weather the boards put upon the boat’s side within two or three days from being sawn out, as no timber we are acquainted with parts sooner with its moisture than larch; and the boards do not work or bend pleasantly when dry. When dried, the thin larch board is at once strong, tough, durable, and extremely light. The tough strength, almost equalling leather, is owing to the woven or netted structure of the fibre of the wood, entirely different from the pine, whose reedy structure runs parallel with very slight connecting or diverging fibres. It is very difficult to split larch even by wedges.

For rural purposes generally, larch is incomparably the best adapted timber, especially for rail or fence, or out-door fabric exposed to wind and weather. It is also getting into use for implements of husbandry, such as harrows, ploughs, and carts. We have seen a larch upright paling, the timber of which, with the exception of the large charred posts, {103} had only been eight years in growing, standing a good fence, sixteen years old, decked out by moss and lichen in all the hoary garniture of time.

In the construction of buildings, larch is valuable only for the grosser parts, as beams, lintels, joists, couples. For the finer boarded part, it is so much disposed to warp, and so difficult to be worked, as generally to preclude use. It is, however, asserted that if larch be seasoned by standing two years with the bark stripped from the bole before being cut down, that the timber becomes manageable for finer house work.