"When the plates have been repaired several times, they acquire a degree of hardness which renders it necessary to anneal them, especially when they pass from one size to another; sometimes they do not acquire the proper quality until they have been annealed several times. Notwithstanding all the precautions which are taken in preparing the plates, the steel still varies a little in hardness, and according to this variation they should be employed for drawing either steel or iron-wire; and if the workman who proves them finds that they are too soft for either the steel or iron, they are put aside, to be used by the brass-wire drawers.
"A plate that is best adapted for drawing of steel wire is often unfit for the iron; for the long pieces of this latter metal will become smaller at the extremity than at the beginning, because the wire, as it is drawn through the plate, is insensibly heated, and the adhering parts are swelled, consequently pressed and reduced in size towards the latter end. The plates that are fit for brass are often too soft for iron, and the effect resulting is the reverse of that produced by a plate that is too hard.
"The smallest plates which Messrs. Mouchel use are at the least two centimetres, or eight-tenths of an inch, in thickness, so that the holes can be made sufficiently deep; for when they are of a less thickness they will seize the wire too suddenly, and injure it.
"This inconvenience is much felt in manufactories where they continue to use the plates for too long a time, as they become exceedingly thin after frequent repairs. One of Messrs. Mouchel's large plates reduces 1,400 kilogrammes (3,080 lbs. avoirdupois) from the largest size of wire to No. 6, which is of the thickness of a knitting-needle; 400 kilogrammes (880 lbs.) of this number are afterwards reduced in one single small plate, to No. 24, which is carding-wire; and to finish them, they are passed through twelve times successively. Wires are frequently drawn so fine as to be wrought along with other threads of silk, wool, or hemp; and thus they become a considerable article in the manufactures."
"Dr. Wollaston, in 1813, communicated to the Royal Society, the result of his experiments in drawing wire. Having required some fine wire for telescopes, and remembering that Muschenbrock mentioned wire 500 feet of which weighed only a single grain, he determined to try the experiment, although no method of making such fine wire had ever yet been published. With this view, he took a rod of silver, drilled a hole through it only one-tenth its diameter, filled this hole with gold, and succeeded in drawing it into wire till it did not exceed the three or four-thousandth part of an inch, and could have thus drawn it to the greatest fineness perceptible by the senses. Drilling the silver he found very troublesome, and determined to try to draw platina wire, as that metal would bear the silver to be cast round it. In this he succeeded with greater ease, drew the platina to any fineness, and plunged the silver in heated nitric acid, which dissolved it, and left the gold or platina wire perfect."
In 1819 a patent was taken out by Mr. Brockedon, for mounting the wiredrawing plates with diamonds, sapphires, rubies, and other hard gems; in these conical holes were to be drilled, with their extremities rounded off, which were afterwards to be polished by the processes known to lapidaries. By these means it was expected the wire might be more equally and cylindrically drawn, owing to the impenetrable hardness of the gems, which would not sensibly wear from the same cause.
As the repeated annealings to which iron wire is subjected, to cause it to yield to the resistance of the draw-plate, would be destructive of the property from which steel derives its utility, steel wire, therefore, during the process of annealing, is surrounded with charcoal-dust from which carbon is reabsorbed in the furnace; thus the metal is rendered very soft and yielding, without losing its steel property.
Among the curious and important "results of machinery" might be mentioned the manufacture and application of steel wire to the making of the hair-springs of watches. "A pound of crude iron costs one half-penny; it is converted into steel; that steel is made into watch-springs; every one of which," it is said, "is sold for half a guinea, and weighs only the tenth of a grain, after deducting for waste, there are in the pound weight about 7,000 grains; it therefore affords steel for 70,000 watch-springs, the value of which, at half a guinea each, is 35,000 guineas!" Now as there are 504 half-pence in a guinea, the pound of crude iron has increased 17,640,000 times in value.
The looms employed for weaving wire-cloth are not essentially different to the looms employed for weaving other filaments, and several patents have been taken out for modifications of the power-loom, to adapt it to weaving of wire; which are described in the Repertory and Journal of Patent Inventions.
The application of wire-gauze to the manufacture of baskets, dish-covers, and a great variety of useful articles, took place about ten years ago, under a patent granted to Mr. Gosset, of the Haymarket, London, who brought the invention from abroad. The annexed cut is explanatory of the process of conversion.
The operation is exceedingly simple, being performed entirely by forcing the wire-gauze between moulds of the required shape, by the power of a screw press, which causes the figure or pattern thus given to it, to be permanently retained after the article has been withdrawn from the mould. We extract the following from the specification before us: -
"It consists of a pattern or block a, of metal, wood, or other suitable material, which is formed on the exterior surface to the desired shape and size of the article intended to be produced. The block a has a screw b, projecting up from the top or crown thereof; c represents a pattern or mould made in like manner, of any suitable material; the interior surface of this mould is formed to the desired shape of the article intended to be produced, and has an aperture made in the crown thereof, so as to be capable of passing over the screw b, and thus permit the mould c to come down over the block a, as shown in the figure.
The manner of using the machine is as follows: the metallic wire-gauze or other material, (which is intended to be shaped,) has a hole made through it, and is passed over the screw b, so as to rest upon the crown of the block a, as seen at d d. In this situation, the upper mould b is placed upon the said metal or gauze-wire, with the screw passing through its aperture, as aforesaid; and the nut or handle c is put on its place, and is turned down upon the screw b, by which means it presses down the upper mould c upon the metallic wire-gauze, or other material, and thereby forces it into the cavity or space between the block a and mould c, so as to give it the desired shape of the article required. The apparatus is then inverted, and placed upon a bench, or other convenient support, with the screw b projecting downwards; and a ring or hoop of tinned wire, or other suitable material, is inserted within the lower edge of the article, and is soldered, or otherwise securely fixed, to the wire-gauze or other material, of which the article is formed. The nut e may then be screwed to the back of the screw b, and the mould and block may be separated, so as to take out the article, which will be found to retain the pattern or shape given to it by the said mould or machinery.
After this, the portions of the metallic wire-gauze, or other material, which may happen to project beyond the edges of the aforesaid hoop or ring, are to be cut off all round evenly, and a small ornamental band of metal, or other material, may be soldered or otherwise fixed upon the exterior edge of the article, so as partly to conceal the interior hoop or ring, and render the whole neat; and then, to finish and complete it, a small nut or button may be fixed through the aperture in the crown, for the convenience of carrying the articles by. Articles of this description will be found very serviceable for covering up delicate commodities, or articles of food, to preserve them from the effects of flies, and for a great variety of useful purposes."
The specification then proceeds to describe anotner slight variation from the above method, for "producing articles of such a description as will not admit of a hole or aperture being made in them." For this purpose, the actuating screw is made to pass through a fixed nut in an iron frame, the end of the screw entering the flat or lower side of the block, which is forced into the cavity of the mould, with the wire-gauze between them. The patentee concludes by claiming as his invention, "the forming or producing of articles of various shapes, patterns, and sizes, out of metallic wire-gauze, or other materials, as aforesaid, by the operation of pressing or forcing the said metallic wire-gauze, or other materials, into moulds or shapes of the desired form of the article intended to be produced; the articles so formed or produced from the metallic wire-gauze, or other material, being caused to retain or preserve the shape or pattern which may have been given to them, by means of one or more hoops or rings, which are secured by solder or otherwise to the edges of the said articles, during the time they remain within the mould."