Of the last kind, fig. 111, page 216, may be taken as an example, in which the parts have no disposition to separate; in this and similar cases the smith often leaves the parts slightly open, in order that the very last process before welding may be the striking the whole edgeways upon the anvil, to drive out any loose scales, cinders or sand, situated between the joints; which if allowed to remain would be either inclosed amidst the sound parts of the work, or would partially prevent the union.
In works that have accidentally broken in the welded part, the fracture will be frequently seen to have arisen from some dirty matter having been allowed to remain between them, on which account, shuts or welded joints extending over a large surface are often less secure than those of smaller area, from the greater risk of their becoming foul. In fact, throwing a little small coal between the contiguous surfaces of work not intended to be united, is a common and sometimes a highly essential precaution to prevent them from becoming welded.
The conical sockets of socket chisels, garden spuds, and a variety of agricultural implements, are formed out of a bar of flat iron which is spread out tideways or to an angle, with the pane of the hammer, and then bent within a setmi-circular bottom tool also, by the pane of the hammer, to the form of fig. 121; after which the sockets arc still more curled up by blows on the edges, and "are" perfected upon a taper pointed mandrel, so that the two edges slightly overlap at the mouth of the socket, and meet pretty uniformly elsewhere, as in fig. 122; and lastly, about an inch or more at the end is welded. Sometimes the welding is continued throughout the length, but more commonly only a small portion of the extremity is thus joined, and the remainder of the edges are drawn together with the pane of the hammer.
In making wrought-iron hinges, two short slits are cut lengthways and nearly through the bar, towards its extremity; the iron is then folded round a mandrel, set down close in the corner, and the two ends are welded together. To complete the hinge, it only remains to cut away transversely, either the central price or the two external pieces to form the knuckles, and the addition of the pin or pivot finishes the work.
Musket barrels, when made entirely by hand, were forged in the form of long strips about a yard long and four inches wide, but taper both in length and width, which were bent round a cylindrical mandrel until their edges slightly overlapped; they were then welded at three or four heats, by introducing the mandrel within them instantly on their removal from the fire at the proper heat, in order to prevent the sides of the tube from bring pressed together by the blows of the hammer.
They have been subsequently, and are now almost universally welded by machinery at one heat, and whilst of the length of only one foot, as on removal from the fire the mandrel is quickly introduced, and the two arc passed through a pair of grooved rollers: they are afterwards extended to the full length by similar means, but at a lower temperature, so that the iron is not so much injured as when thrice heated to the welding point.
The twisted barrels arc made out of long ribands of iron wound spirally around a mandrel, and welded on their edges by jumping them upon the ground or rather on an anvil embedded therein. The plain stub barrels are made in this manner, from iron manufactured from a bundle of stub-nails, welded together and drawn out into ribands to ensure the possession of a material most thoroughly and intimately worked. The Damascus barrels are made from a mixture of stub-nails and clippings of steel in given proportions, puddled together, made into a bloom, and subsequently passed through all the stages of the manufacture of iron already explained; to obtain an iron that shall be of unequal quality and hardness, and therefore display different colours and markings when oxidized or browned.
Other twisted barrels are made in the like manner, except that the bars to form the ribands are twisted whilst red-hot like ropes, some to the right, others to the left, and which are sometimes again laminated together for greater diversity; they are subsequently again drawn into the ribands and wound upon the mandrel, and frequently two or three differently prepared pieces are placed side by side to form the complex and ornamental figures for the barrels of fowling-pieces, described as " stub-twist, wire-twist, Damascus-twist," etc, which processes are minutely explained and figured by Mr. Greener.*
All these matters are also explained in Mr. Wilkinson's recent and interesting work,† which likewise treats of one method amongst others of the formation of the Damascus gun barrels; by arranging twenty-five thin bars of iron, and mild steel in alternate layers, welding the whole together, drawing it down small, twisting it like a rope, and again welding three such ropes, for the formation of the riband which is then spirally twisted to form a barrel, that exhibits, when finished and acted upon by acids, a diversified laminated structure, resembling when properly managed an ostrich feather.
Let me now turn from these engines of destruction to a modification of one of them to a happier purpose. When the illumination by gas was first introduced in the large way, by Aaron Manby, Esq., then of the Horsley Iron Works, the old musket-barrels, laid by in quiet retirement from the fatigues of the last war, were employed for the conveyance of gas; and by a curious coincidence, various iron foundries desisted in a great measure from the manufacture of iron ordnance, and took up the peaceful employment of casting pipes for gas and water.
* Greener •' On the Gun," 1835; and Greener "On Gunnery," 1841. † "Wilkinson's Engines of War," 1841, pp. 89 - 98.