Mr Monteath states that Scots fir should not be thinned to greater distance than 20 feet apart, and larch 15 feet. This shews very little consideration: the distance apart necessary for these kinds of timber, and of all other kinds, must be relative to the soil, situation and climate, and the intentions of the owner, whether he means to bring them soon to {152} market, or carry them forward to great timber. When fir trees are intended to be early cut down, or when disease in larch from unfitness of soil may be apprehended, as it is thence of small consequence though their future ability to become great timber be destroyed by closeness, the plants should be retained pretty near each other from the first, that the timber may be tall, straight, and clean. On the other hand, when the soil is suitable and great timber intended, early attention to thinning and great openness from the first is absolutely necessary, as they (the firs), different from other trees, can never repair the loss of their lower branches by throwing out new ones from the naked stem; and double the distance stated by Mr Monteath at least for larch, which, instead of less, needs more space than Scots fir, will be required. We believe the decay of Scots fir, occurring so generally at about 40 years of age, although also dependent on inferior variety and kiln-drying of cones, arises principally from want of timely thinning; that is, that the infirm variety of Scots fir in common use, when supported by numerous feeders, and not weakened by being drawn up into a tall slender stem, will often have hardihood to continue growing, and acquire considerable size in our cold, wet, moorish tills, or even in our moorish {153} sandy flats. Many casualties will, however, occur among resinous trees[37], especially in unsuitable soil, even when the plants rise from the seed naturally sown, and have sufficient room for lateral expansion. The same cause, viz. closeness or want of thinning, induces early maturity, old age and decay in larch, although it does not seem to have any influence, either as inducement to, or prevention of, the rot. We have heard men,—even men reasonable on other subjects—speak of allowing a pine wood to thin itself: as well might a farmer speak of allowing his turnip field to thin itself. When woods are planted of various kinds of timber, the stronger, larger growing kinds will sometimes acquire room by overwhelming the smaller: but when the forest is of one kind of tree, and too close, all suffer nearly alike, and follow each other fast in decay, as their various strength of constitution gives way; unless, from some negligence or defect in planting, a portion of the plants have come away quickly, and the others hung back sickly for several years, so that {154} the former might master the latter: or when some strong growing variety overtops its congeners. In the natural forest of America, when a clearance by any means is effected, the young seedlings, generally all of one kind, spring up so numerous, that, choaking each other, they all die together in a few years. This close springing up and dying is sometimes repeated several times over; different kinds of trees rising in succession, till the seeds in the soil be so reduced as to throw up plants so far asunder as to afford better opportunity for the larger growing varieties to develope their strength; and, overpowering the less, thus acquire spread of branches commensurate to the height, and thence strength of constitution sufficient to bear them forward to large trees.
Mr Monteath, apparently to encourage the destruction of young oak, and keep his merciless hatchet agoing, asserts that “oak trees, at the age of 24 or not exceeding 30 years, have as thick a rind or fleshy part of bark, as when they arrive at 50.” If by this he means to say, that the useful part of the oak bark of the stem of a tree at 50 years old is no thicker than that of one of 30, we say he is wrong, widely wrong. A thriving oak tree of 100 years will still continue to increase the thickness of the valuable part of the bark on the stem, although part of the {155} outer layers or cuticle may lose vitality, and become corky. We have taken down a luxuriant growing oak, exceeding three feet in diameter, the living bark of whose stem was about two inches in thickness, resembling thick plank, and which was considered by the tanners much stronger in quality than bark of younger growth. Has Mr Monteath seen any bark resembling this on 24 years old sproutings? If, by the above quotation, our author means to say, that the valuable part of the bark on the branches of a tree 30 years old, is equal in thickness to that on the same sized branches of a tree at 50, we say he errs still; that is, provided the older tree be in a healthy thriving condition, and growing equally open and exposed as the younger. Trees, as they increase in years, increase also in the thickness of the living bark, from the root upwards to the smallest twig, provided they have not begun to get dry and sickly from over maturity. When this period arrives, the living part of the bark upon the stem and larger branches becomes very thin, with a great proportion of dead corky substance; although, on the twigs and smaller branches, it still continues to thicken. The age at which the external part of the bark begins to lose vitality, is considerably dependant upon luxuriance of growth, climate, and exposure; and the {156} period when this loss proceeds faster than the annual increase within, is altogether dependent on the vigour of the tree, not on the age, and never takes place till the timber is ripe for the dock-yard.
We would warn the readers of Mr Monteath’s volume, that his calculations and statements regarding the worth of coppice and timber generally, seem more suited to flatter the owner’s wishes than to be useful to him as a merchant; or to be adjusted to the value of money during the late war—not to the present value. We also do not very well comprehend his re-establishment or resuscitation of life in dead trees. We observe several other slight errors, such as the duration of his paling,—and the affirmation that the sap-wood will not extend so as to cover over the section of a pruned branch which contains any red or matured wood. Most readers will be able to detect such errors as these.
In taking leave of Mr Monteath’s volume, we would offer our acknowledgment for the attention he has bestowed on the subject of the seasoning of timber, by steaming with extract of wood (pyroligneous acid) and by scorching, as prevention of dry rot. The greatest objection we see to his plan is, that all timber dried quickly is liable to crack and split, and loses a considerable portion of its {157} toughness and elasticity; at least, timber when dried slowly is harder and stronger than when dried quickly, the dryness in both cases being carried to the same extent. The comparative strength of timber scorched and timber not scorched, after both are soaked in water, as in the lower timbers and plank of vessels, should be subjected to experiment.
Our author’s directions (although the practice is also not new) to season larch by peeling off the bark one or more years previous to cutting, in order to prevent it from warping or twisting in framed housework; and his hints recommending stripping off the bark from most kinds of timber a season previous to cutting, are also deserving of notice. We greatly wonder that something efficacious has not been done in regard to dry rot by our Navy Board, and consider the subject of such importance, that we think a rot-prevention officer or wood physician should be appointed to each war vessel from the time her first timber is laid down, to be made in some shape accountable if rot to any extent should ever occur; and that this officer should be regularly bred to his profession at an institution established for the study of this branch of science at the King’s largest building yard. Perhaps it might be as well to endow several professors’ chairs at the universities to follow {158} out and lecture on this science, as being of far more importance than many which are already endowed. We think that steeping in fresh water pits for several years, till a kind of acetous fermentation take place in the timber, or till it become of a blue colour; or in tan-pits; or for a shorter period in strong brine pits; or even salting the timber like herrings, after it is blocked out; or forcing pyroligneous acid, or composition of chlorine, or other solution, antiseptic or obnoxious to life, into the pores of the timber when dry, by pressure; or perhaps by charring the timbers after they are cleaned down on the stocks ready for the plank, by playing on them a jet of flame from a flexible gas pipe,—might, some of them, be found preventive of the rot, and at same time not to impair any of the valuable qualities of the timber.
We are a little shy in committing ourselves, lest we should be impressed as a dry-rot physician or professor; but if the following plan for preservation of vessels when unemployed has not already been tried, we recommend it to the notice of our Navy Board.
Let every part of the vessel be cleared out, and every port-hole or external opening be made as air-tight as possible.
Let a quantity of recent-burned limestone {159} (lime-shells) be spread thin over every inside deck or floor, and over the whole bottom and sides of the vessel, and every door or hatch in the main-deck be immediately closed down air-tight. A number of rods or shreds of timber would require to be nailed slightly to the inside skin of the ship where the slope is considerable, in order that the lime-shells may rest and not roll down.
As soon as it is found that the lime-shells are completely slaked—become hydrate of lime—let it be sold to the farmer or house-builder, or be used in any government erection going forward at the time; and let another quantity be laid in. We would consider a sloop of 80 tons load of lime, value, prime cost and freight, about L.70, would suffice for covering the internal surface of a seventy-four gun ship. When slaked to powder, the lime might be disposed of at little loss. It is impossible, without trial, to say how often the lime would require renewal, but we think twice or thrice a-year would suffice to preserve the vessel dry and free of any corruption; perhaps even once might be found effectual. Suppose that the lime was renewed every four months, and that when slaked it only sold at two-thirds of the whole cost, the preservation of a line-of-battle ship would be nearly as follows. The price of the lime {160} and work is correct, according to the rates in most of the harbours of Scotland.
A quantity of rods or shreds of timber, about three inches in diameter, for nailing on the sloping sides of the vessel, material and labour, | L.20 | 0 | 0 |
Eighty tons lime-shells = 560 bolls, at 1s. 7d. per boll, prime cost, | 44 | 6 | 8 |
Freight of 560 bolls, at 1s. | 28 | 0 | 0 |
The slaked lime is supposed to sell at 2-3ds of the cost, thence the whole loss on a year would equal the value of one cargo. | |||
Carrying three lime cargoes of shells aboard, and spreading them, | 30 | 0 | 0 |
We allow here for the greater distance of carriage, and spreading out of the cargo, nearly thrice the sum requisite to remove lime-shells from a vessel into a cart. | |||
Removing the slaked lime of three cargoes, | 30 | 0 | 0 |
| Cost first year, | L.152 | 6 | 8 |
| Deduct rods, | 20 | 0 | 0 |
Cost, second, and each following year, | L.132 | 6 | 8 |