This iron has long been held in great esteem. It looks pretty; but certainly does not possess either the strength or tenacity of wire-twist iron. It is well known that the strength of a rope may be destroyed by twisting it too much: so is it with this sort of iron. Iron is best when not twisted at all: I speak of the bar. It resembles wood, inasmuch as the strands or fibres run parallel, firmly adhere, and add strength to each other; if you twist those fibres you tear them asunder, and they no longer support each other. So it is with iron.
The objection made to the wire-twist is, that owing to the iron and steel being perfectly separate bodies running through the whole thickness of the barrel, there is a difficulty in welding them perfectly; and, of course there is danger of their breaking across, at any trifling imperfection or mis-weld. This objection is certainly well grounded, as many barrels break in the proving. I have seen a very strong barrel indeed broken across the knee without the slightest difficulty, while, to all appearance, it was perfectly sound. This is the reason why the manufacturers have ceased to make them, except for the American trade.
It may be said that the fibres in the Damascus, after being torn asunder, are welded anew. True; but could you ever glue the fibres of a piece of wood (twisted in the same way) together again, to make them as strong as before? No: cut several pieces of wood across the grain and glue them together, you would not expect them, though equal in substance with a piece in which the grains run lengthwise, to be of equal strength. In short, I hold a Damascus barrel to be little superior to a common barrel, in which the fibres run parallel to the bore.
All the varieties of figured barrels are but modifications of Damascus. The most endless variety possible may be attained; a figure with the carbonised material, showing only the ends or edges of the various laminæ, or portions of the face of that laminæ, may with equal facility be obtained, if the patience of the artist be in proportion. It would be a never-ending task, a subject for many volumes, to endeavour to describe a tithe of the varieties that might be, and have been made.
The Belgians are very expert at this sort of ornamental work. The very minute Damascus figure they frequently produce, is admirable, if beauty alone were the advantage sought in a gun barrel. They use thirty-two alternate bars of steel and iron, and roll them into a sheet of 3-16ths thick, and then slit them by a machine into square rods; these are twisted in the way just described, but to such an extreme as to resemble the threads of a very fine screw: six of them are welded into one, instead of three as with us. The figure is so extremely fine as to appear not to be larger than the finest needle. I have seen barrels made in Liege, superior in minute figure to any real Damascus barrel, or sword either. Our workmen here say the steel is better; which I am inclined to think is true: it is a branch of the gun manufacture they have long excelled in. The very best “Damascene” workers are to be found at La Chafontaine, a few miles from Liege, where they dwell in as beautiful a dell as fancy could wish, with a powerful hill-stream working their boring and grinding-mills, thus enabling them to send their barrels into Liege, ready for the filer. I have spent considerable time, and taken great trouble, to produce in Birmingham iron equally good; and I have succeeded: but, unfortunately, Englishmen are so extravagant in their ideas of value, as to render the constant manufacture of this iron here, a losing speculation. It can, however, be obtained from Belgium now, under the amended tariff, at ten per cent. on the value. It can be purchased there, ready for barrel making, at a franc per pound; and cheap it is at that price: two and a half francs would not purchase it here.
That Damascus iron is incompatible with goodness, I can and shall clearly prove. Experiment with the testing machine shows a rod of wire-twist 3-8ths square, containing 1·6875 solid inches, as equal to a tension of 11,200 lbs.; whereas a rod, when converted into Damascus of 11-16ths of an inch in breadth, by 4-16ths in thickness, containing 2·625 solid inches, was only equal to 8,960 lbs.; thus showing a clear loss of full thirty-five per cent. And when welded into barrels of the dimensions described, the relative internal strength of each is 5,0191⁄2 lbs., and 3,292 lbs. to the inch of tube. This constitutes a great difference. But unfortunately that is not all.
In the preceding chapter I noted the fact, that all sorts of iron lose a portion of their strength by being heated or softened; but I found that Damascus suffered more than any other sort of iron, excepting the common kinds. For instance, the bar of wire-twist would, in the state it came from the rolling mill, bear 11,200 lbs., but, after softening, it would only bear 10,180 lbs., being a diminution of 10 per cent. A bar of Damascus suspending a weight of 8,940 lbs., the measure of its strength, when annealed, was 7,840 lbs., being a falling off of 121⁄2 per cent. Thus, I trust I have clearly shown, that whatever other quality Damascus possesses, strength is not one of its properties. It must not, however, be supposed that the above weight indicates its greatest strength; on the contrary, its strength can be increased full 221⁄2 per cent. by cold hammering. Still, however, it will only hold its relative position to other kinds of iron with respect to strength, since they are all capable of having their strength increased by the same process.
Damascus barrels have fallen much into disuse, being rarely seen except as pistol barrels,[10] which, together with a great quantity of counterfeits, are made for the South and North American trades, in the shape of double and single guns of a flashy appearance—all invariably veneered or plated with ribbons of this ornamental iron. I shall now dismiss this subject; after remarking, that certainly a very handsome barrel may be made after this principle, if too much twisting be avoided. It has been seen that the rods are twisted until there is fourteen turns in the inch of length: an excess productive of the detrimental effect mentioned; while, had there been but two turns, a large proportion of strength, if not all, would have been retained. One turn only, under the same circumstances, would very likely be highly beneficial; indeed I have found it to be so: one twist binds the interior strands, as the outer does the interior in a rope, and thus adds strength. This shows that there is a medium in all things.