We copy from the Engineer an engraving and description of one of six bridges over the Avon on the Mangotsfield and Bath branch of the Midland Eailway. They are supported in the centre on cast iron screw piles. The engravings represent the bridge known as No. 2. It rests on abutment piers at each end ; the middle pier is formed of a stack of twelve piles, which have screw blades prepared on a special system by Messrs. Handyside Co., of Derby, who supplied and constructed all the six bridges. The superstructure consists of fourteen lattice girders, which, with their bracings, weigh 218 "tuns. The piles weigh, sixty-six tuns, and the girders by which they are united at the top, and the centrals. carrying the superstructure, weigh forty-one tuns. The main girders are surmounted by a handsome open railing. Eeferring to our engraving, we have at Fig. 1 an elevation of bridge No. 2 ; and at Fig. 2 a plan, with a portion of the platform removed, and showing also a footway beyond the lines of rails. Fig. 3 shows an elevation of the screw piles, which are two feet diameter, and are filled in with concrete. Fig. 4 shows the parapet railing in elevation and detail, from which will be seen its connection to the main girder. It may be as well, before concluding, to say a few words upon the manner in which the screw piles of these bridges were fixed. In some instances they pass through beds of rock from ten inches to twelve inches thick, and in all cases they passed through blue lias and red clay. Each pile was held in place while being screwed down by a strong timber framing. Instead, however, of the usual capstan, rope, and winch arrangement for screwing, Messrs. Handyside use a special apparatus of their own design. Having experienced the difficulty of keeping the two ends of an elastic rope equally taut, and finding, moreover, that the winches were sometimes unable to exert sufficient power, they devised a machine by which both ropes and winc%es are dispensed with. It consists of an, arrangement of worm wheels and gearing, and admirably overcomes all the difficulties of the ordinary system, iand prevents those occasional jerks which are so undesirable in the operation of screwing. All the six bridges were designed by Mr. J, S. Crossley, the engineer to the Midland Eailway Company; their supply and construction being intrusted by Messrs. Eckarsley and Baylis, the contractors for the line, to Messrs. Handyside Co., to whom we are indebted for drawings and particulars. Although there are no strictly novel features about these bridges they deserve attention as examples of the best modern practice. We need scarcely add that the workmanship is excellent. A new method for graining has been recently patented in England, applicable to transferring impressions from wood to plain deal, or to painted surfaces, either liat or molded, in buildings of all descriptions, where an accurate transcript of the more costly woods is desired, and for house and bedroom furniture generally ; for japanned goods, made in metal or papier mache ; for enameled parqueterie tiles, and for articles in earthenware, such as garden seats, oyster and flower tubs, spirit casks, flower pots, tea-urn stands, etc. ; for enameled slate, for paper hangings, and for oil cloths. The inventor thus describes the process. Select a piece of wood of fine quality, about five feet long, twelve inches wide, and one-fourth inch thick it is, to use the technical phrase, j cleaned up by the cabinet maker on both sides, and is well sand-papered down. By having both sides of the board cleaned up, two patterns are obtained from the same board. A chemical preparation is then applied to it, which has the effect of opening the pores of the wood, and, at the same time, of hard ening the surface, and, when the board is thoroughly dry, it is ready for use, and is, in fact, a wood plate, " not graven by art or man's device," but by the great Designer and Architect of the universe, whose works, the most stupendous as well as the most minute, are all perfect. The material used for taking the impression is prepared in oil, and is specially adapted for the purposes of transferring.. The paper, too, manufactured for the purpose, is very thin but tough, so that it can be successfully applied to any irregular or molded surfaces, and it is sized to prevent the color from becoming incorporated with the body of the paper. A small wood roller is used for spread ing the color on the board, and a large, broad, flexible palette knife is used for taking the superfluous color off. That being done, the sized paper is placed on the board, and both are passed through a small machine having turned iron cylinders, the upper one being covered with double-milled flannel; the paper is then taken off the board, its printed surf ace is applied to the article to be decorated, the back of the impression is lightly rubbed with a piece of soft flannel, the paper is removed, and an exact fac simile of the board, from which the impression is taken, is given. But that is not all, for a second and a third transfer are frequently obtained from the same piece of paper, and sometimes a fourth, a fifth, and a sixth. This is one pi the remarkable features of the process, and, as you Will not fail to perceive, must have a very marked influence on the rapidity of its application, and, consequently, on its cheapness. With the color properly prepared, and adapted for its purpose, the plate does not clog or become foul any more than does the plate of the copper and steel-plate printer ; but such a result would occur in both cases if the material used was not suitable for its purpose. When a board has been used it is treated as all other plates are, a cheap material is used for dissolving the printing color, a handful of fine sawdust is then rubbed over it, which most effectually draws out of the pores of the wood the dissolved color, and leaves the board clean, and ready for further use when required. Under the same conditions, provided no accident happens to it, the board will be far more durable than either the copper or steel plate. Charcoal Pipes The use of charcoal in the preparation f pipe heads, a long time practiced, has lately experienced many improvements, so that now pipes are produced remarkable for a deep black, lustrous appearance, and of very great durability. The^material consists of a mixture of two parts of the best charcoal black and one part of the best black peaty earth, ground so finely that, when rubbed between the fingers, no trace of granules is perceptible. Two parts of this mixture are then united with one part of an equally well pulverized residuum of distilled cannel coal, containing still a portion of its bitumen, and the whole rubbed together thoroughly till all the three ingredients are uniformly combined. The mixture is then placed in iron boxes, in which are sunken molds corresponding to the pipe heads, and while the boxes are then heated to the boiling point of water, stamps with rough surfaces are pressed under hydraulic pressure into the openings of the heads, so that this process, united with the increased temperature, not only combines the carbonaceous mass into compact pipe heads, but also produces a smooth, exterior, and at the same time a rough inner surface.
This article was originally published with the title "Iron Railway Bridge Over the Avon, Xylograpny, or Printing and Graining from the Natural Surface of the Wood, and more" in Scientific American 20, 14, 209 (April 1869)