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.