During the period in which the Second Volume of this Work has been patting through the press, various new and additional matters having relation both to the first and second volumes have come under the author's notice; the more important of these additions are here given. By inserting in the body of the first edition of the work referenences follows: - see Appendix note H. - note I, etc., at tht pages respectively designated, the notes will come under observation at their appropriate places in the text.
Note H, Page 22 - To follow the Foot Note.
In this process, which is now more resorted to then others for this purpose, several pieces of timber are arranged side by side on a sledge, bound together by hoops and chains, and thus introduced upon a railway into a long cylindrical iron Teasel, the cover or end of which is then screwed on air-tight Steam is now admitted, first to drive out the air, through a valve opened for the purpose, and then to form a vacuum, which partially occurs when a little of the cold solution of sulphate of iron is pumped into the vessel, by means of the steam engine, to condense the steam; the vacuum is then completed by an air pump, the liquid flows in as the air is exhausted, and is ultimately subject to pressure by force pumps also worked by the steam engine: this fills all the pores of the wood with sulphate of iron. After a few minutes the sulphate is allowed to flow out of the tank by the re-admission of air, the vessel is again heated with steam, and is similarly filled with muriate of lime.
A double decomposition instantly occurs with in the ports of the wood, as the muriatic acid goes over to the iron, forming muriate of iron, and the sulphuric acid proceeds to the lime, forming solid sulphate of lime or gypsum, the latter remains principally in the pores, whilst the muriate of iron pervades the wood generally. The entire process of preparing the timber, including the filling and emptying of the tank requires from one to three hours, according to the size of the cylinder. The wood becomes much heavier, indisposed to decay, less combustible, darker in colour, and also proof against rot and the ravages of insects.
By certain variations of the process, and the employment of some other salts, the light coloured English woods may be stained in a variegated manner throughout their substance, so as to be available for making ornamental furniture, but the principal application hitherto made of the process, (for which the patent was specified in January 1842,) is for preparing timber for railway purposes, and for building, especially the wood used in piles and wet foundations.
Mr. Payne has a new patent, which will be shortly specified, designed for a different preparation of timber for the sheathing of ships and see walls.
Note I, Page 25 - To follow the Foot Note. (The Bassiilih or Indian Adze.) " By far the handiest instrument, (said the late Sir John Robison.) for blocking either hard or soft wood for the lathe, is the Bsssoolah or Indian adze, with a head of from 1 3/4 to 2 pounds weight The eye is conical and made widest at the upper end, so that the handle may be knocked out to allow of the adze being ground."
The Bassoolah is represented at d fig. 318, page 473, of this present volume.
Notes J, K, L, Page 46 - To conclude the Page. Note J. - Mr. Irving's Carving Machine.
Since the period at which Messrs. Braithwaite's patent for carving wood by burning was granted in Nov. 1840 (see Note A, Appendix vol. i.) two other important patents have been taken out for carving wood by revolving cutters, and on each of which patents a few words will be now offered.
Mr. Irving's Patent, sealed November, 1843, although it may be used for figures in low or high relief, is principally applicable to works in one plane, such as the mouldings of Gothic tracery, whether straight, curved, or undercut, and of all sections; the work is generally executed from templets or pattern plates.
The revolvingdrill, or cutter, which is made globular, elliptical, or of the particular section of the moulding, is mounted on a vertical axis at the end of a swinging arm or lever, which is jointed to the solid framing of the machine. The wood or other material to be carved, is fixed towards the edge of a circular table that is free to move on a vertical and central post. The arm with the drill is capable of being adjusted vertically by means of a treadle, to make the tool penetrate more or less deeply into the work.
As therefore the drill may be moved in one arc, Bay nearly from east to west by swinging the arm upon its axis, and as the work may also be moved in another arc, nearly as from north to south, by swinging the table round upon its axis, and as these two motions may be accomplished simultaneously and in any relative degrees by the two hands, any outline that has been drawn on the work may be readily followed with the drill or cutter. But more usually a perforated templet is affixed upon the work, and the end of the cylindrical spindle or drill socket is allowed to rub against the templet, in order that the drill may cut away all the material between the interstices of the templet, and which latter mode is much the more rapid and exact, especially when many copies of the same work are required.
Many of the mouldings both in wood and soft stone, that are used in the new Houses of Parliament, are in the course of manufacture by this machine, which is now the property of Mr. Pratt, of London.
Note K, to follow Note J, on Page 46.
Mr. Jordan's Patent Carving Machine.
Mr. Thomas Brown Jordan's Carving Machine, patented Feb. 17, 1845, is more employed for figures and ornaments than for mouldings, and two copies are generally carved at once, the pattern being placed midway between them.