Mr Forsyth’s surgery is of slight importance to timber trees in respect of economy, as with them as with man, it is generally easier to raise up anew than cure the diseased. Yet it is well that the rationale of this practice be understood by foresters, more in regard to prevention than cure; an occasion will however sometimes occur where a tree may economically be benefited by surgical aid: and in cases where the {193} Dryades acquire lasting attachment to particular objects, the science is invaluable, as the object of their love may be thus continued flourishing to the end of time, or as long as the inamorata chooses to pay the surgeon.
Mr Forsyth presents us with numerous models of knives, irons, and gouges, suited to the operation of removing the dead parts of his patients. Where the gangrene occurs in the outside, he hews and scrapes away with these till every portion in which the vital principle is extinct be detached, and the surface all regular and smooth, so scooped out as to afford no hollow where water may rest. He then gives a coating of his composition salve to all the space operated on, wherever the cuticle of the bark has been broken, which prevents the drought, rain or air, from injuring the bared parts till the bark spread over it. In cases where the removal of all the dead part at once would endanger the stability of the tree, he first removes it along the borders of the decayed part all round, close to the sound bark, of such a breadth as to give full room for the bark to spread over in one season, and covers this with his pigment, annually repeating the cutting out, and painting around the rim or edge of the new-formed bark, till the whole of the dead part be cleared away. {194} Under this treatment, the excavation is gradually filled up with the new wood forming under the spreading bark, and the wound becomes cleanly cicatrized. Mr Forsyth has effected complete renovation, where the sound vital part consisted only of a narrow stripe of bark and alburnum upon one side of the stem, and where two cart loads of the diseased trunk had been scooped out.
When the heart of the tree is decayed, he makes a section longitudinally in the side of the tree, as far up and down as the rot extends, and of sufficient width to admit the working out the diseased part; and managed as above, the bark and wood gradually extend from the two sides of the section into the vacuity, and fill it up entirely with new sound timber. When the tree is of considerable diameter, the opening formed in the side of the stem must be wide, nearly extending to half the circumference, otherwise the sides of the section would meet before the bark extended over all the inside. When the bark from the two sides approaches to touch in the bottom of the hollow, he pares off the cuticle from each side where they join, in order that they may unite thoroughly. Should any of the roots be diseased, he removes the earth, and pares away the corrupting parts; and if the top be stunted or {195} sickly, he crops it at the joints where the smaller branches separate, whence numerous fine strong shoots spring forth, whose new vigour of vegetation, and absence of drain by seeding for several years, generally renovate the whole plant, and occasion the filling up of the wounds (should the trunk be under cure) to proceed rapidly.
Need we mention, that it is only in the cases where the partial death or decay has resulted from casualty, or something not connected with the general system of the plant, or with the soil, or other external circumstances (unless these can be changed), that renovation by clearing away the decayed or sickly parts is attainable? Where the plant is sinking from mere old age, a source of decay of which in some kinds at least we have doubts, or from the soil being improper or exhausted for the particular kind of plant by long occupancy, or from any circumstance not admitting of remedy, the attempt to heal up the wounds caused by cutting out the diseased parts, or to induce new vigour by cropping the top, must be abortive, or only attended with partial or temporary success.
Our author, who is a practical man, apparently very little disposed to throw away time upon inquiring into causes, does not attempt even to guess at {196} the mode by which his composition performs the wonders for which he gives it credit. It is impossible, by any salve, to promote discharge from the bare alburnum, though cut into the vital part, to form, or assist in the formation, of bark; and the sum of the resulting advantages consists in preventing the vitality from becoming extinct far inward from the section (as under the best management to a certain extent it will become so), by an antiseptic cover from the drought and moisture, heat and cold; in promoting the spread of the juices from the edge of the bark over the bared part by exclusion of drought, and by forming a defence against insects. We have found a paste of pure clay, wrought up with some fibrous matter, as chaff or short hay, an excellent cover for tree wounds, applied in spring or early summer, when dry weather followed the application; but in autumn or winter, and when moist weather followed, the clay, by remaining wet, only served to induce corruption. We think this clay paste (probably benefited by a powdering of charcoal on the inside) the best application when applied in spring. We have seen a terminal cross section, of about one inch diameter, of a long branch, covered quite over in two months with bark when clayed; and a tree of three inches in diameter, from {197} which a dog had torn off the bark from one half of the circumference of the stem, entirely renew the lost bark in one season, when immediately clayed over. Resins, oils, bitumen, paints and composts without number, have been used with more or less success, depending upon the period of the year, weather, kind of tree, individual health, and other circumstances; but these salves should, as in flesh-wound salves, be considered only as protections, or slightly auxiliary to the restorative energy of nature, not as cures.
V.—MR WITHERS.
Having by chance glanced over a pamphlet by an Englishman, a Mr Withers, we find there has been jousting between that gentleman and our Scottish knights, backed by their squire the Edinburgh Reviewer, in which the discomfiture of the knights has been wrought by simple hands.
It seems Sir Henry Steuart, forgetful that his own bright fame, which rivals that of the discoverers of steam-power and gas[42], though of comparatively quick growth, will endure for ages; and led astray, probably, by the foolish adage, “soon ripe, soon rotten,” had stated unqualifiedly, that “fast grown timber will sooner decay, and is of opener weaker texture than slow grown of the same kind;” and on these false premises concluded, that all culture or application of manure to further the growth of timber is improper—winding up with some patriotic flourish about danger to our war navy, from Mr Withers {199} rendering the British oak of such exceedingly rapid growth as to be soft and perishable as mushrooms. Withers completely demolishes his literary and scientific adversaries, but is, withal, so very imperfectly acquainted with the subject—himself, and also his junto of experienced correspondents, that we shall attempt a few lines in elucidation.
We shall first state our facts, accompanied with explanatory remarks.
No. 1. An ash tree of about 18 inches diameter, and 65 years of age. The first 35 years, the annual growths were of middle size, and the timber weighty and tough; the following 15 years, very small, light, porous, and free; the latter 15 of middle size, and of fair quality. This tree had been growing till about 49 years of age in a grassy avenue, of dry clay soil, and close by a deep ditch. About sixteen years back, the ditch had been filled up, and the ground ploughed and manured regularly till the tree was cut down. After 35 years’ growth, the scorching roots of the ash had rendered the soil so dry, that the tree had run entirely to reproduction: Nearly all the nourishment from the ground assimilated in the leaves being expended in forming seed, no extension of the top had taken place, and {200} thence no thickening of the bole being necessary for support, no wood proper had been deposited on the trunk save the annual rings of lineal tubes to convey the sap, which constituted a brittle light wood, of very slight lateral adhesion[43]. After the ditch was filled up, and the surrounding ground ploughed and manured, the increased supply of moisture and nourishment had induced a considerable new extension of top (which was quite visible in fine young healthy branches rising from a stunted base), and consequent necessary thickening of stem by annual layers of proper dense wood, along with the lineal annual tubes.