The great stride in the manufacture of shoes was that resulting from the invention in 1857 of the McKay stitching machine — a slow operation as previously done by hand. Intro duced into active use in 1861 , it was an im portant factor in supplying the Union troops during the Civil War. This method, which is in use to-day— see statistics at end of this article—and which for some purposes is pre ferred over all others, makes possible the auto tnatic sewing of the outer-sole to the inner-sole —the edges of the upper being between the two — with a strong chain stitch, a furrow or chan nel being cut in the outsole to protect the part of the thread extending to the bottom. Its principal inconvenience is the fact that the threads extend through the insole, making a perceptible ridge which must be covered with a lining, a thin piece of leather or cloth covering the insole. Other machines for ef fecting separate operations were invented at about the same time or subsequently. The leather rolling machine was introduced about 1845, for pressing the leather and giving it the proper consistency, an operation formerly laboriously effected on the lapstone. Following this came the various types of leather sewing machines for stitching the uppers, using wax thread. In 1855 the automatic splitting ma chine was first used— for dividing leather or reducing it to a uniform thickness — follow ing which came the "dieing-out* machine for cutting the soles and various other parts of the shoe by pressure on a fixed pattern. Improve ments were made in pegging and nailing ma chines, particularly in the feeding of a continu ous cable cutting the same off at required lengths. The most important of these is the one used to-day, known as the "rapid standard screw machine.* Devices were perfected for making the individual lifts of the heels, as sembling and nailing them together and on the corresponding part of the sole and finishing the whole. Other machines have been perfected for practically every operation in the making of footwear, one large factory of the United States producing machinery adapted to 170 distinct operations on a single part of shoes, 210 pair of hands being required. The greatest advance, however, from the standpoint of shoe-comfort, has been the so-called ((odyear welt sewing machine,* which, with the manifold improvements of form introduced by last man ufacturers, has produced a shoe with a per fectly smooth interior adapted to feet with irregularities. At the present time there are seven methods of attaching the outer sole to a shoe by machinery: (1) McKay stitching; (2) Goodyear welt stitching; (3) turn shoes (sew rounds — the sole sewed to the upper outside in and then turned), McKay machine used; (4) pegging 'with wooden pegs; (5) "standard screw)); (6) nailed, with inside clinching; and (7) welt, attached to upper, sewed direct to edge of outsole by Goodyear stitch.
Leather.— In the making of footwear an important consideration is the kind and quality of leather, depending more or less upon the methods of and finishing adapted to specified requirements. Flexibility, tensile strength and the possibility of absorbing mois ture are the most important elements. Upon these depend the qualities of wear and com fort— in a word, the reputation of the manu facturer. Of all sole-leathers oxhide is unde niably the best, followed by pig-skin, camel hides and horse-hides. Likewise, for the uppers of heavy shoes calfskin is the standard, while for light shoes goatskin has the preference, closely followed by sheepsldn. The ten* "hides' is applied to the larger full-grown ani mals of the bovine group, and to horses and camels, while "kips' is the term used with re lation to the skins of the smaller animals, some of which belong also to the bovine class. In addition to the foregoing the skins of the kan garoo and many other animals, and even fish, have been utilized. Of the latter, the porpoise and shark seem most suitable, and the United States government is at present making a series of experiments with a view of utilizing shark skins on a large scale. Lately efforts have been
successfully made to use composition soles —of rubber mixed with a large proportion of fibre — and for uppers, canvas and other cloths have been found a suitable substitute for leather.
Processes of Manufacture.— The opera tions of the Goodyear welt process of shoemak ing are substantially as follows: On the re ceipt of each order, the specifications are en tered in the corresponding order book and given a number. Tags, one for each case of shoes, bearing the same number, with details, are sent to the foreman of the cutting room; others to the sole room, and a third lot to the bottom ing,' or assembling, room. The foreman of the cutting room selects and has the material for the uppers cut to the required measurements. This cutting to size is done by steel dies under heavy pressure on what is known as a °clicking° machine. In addition to cutting, they also mark the leather as a guide for assembling. The next operation is that of 'skiving,' or beveling the edges, after which they are coated with cement and folded on a 'folding' machine. For orna mental purposes perforations are generally re quired — particularly on the tips, or toe-caps, and on the upper stitching edge of the vamp. This is done respectively with an automatic 'tip punching' or 'perforating' machine. Either is capable of malting these perforations in the form of designs, the latter being similar in operation to a sewing machine. In the mean time, the linings of cloth or leather, having been cut according to instructions and stamped with order number, are given, along with the other, outer parts of the upper, to the stitchers, who, on sewing machines specially adapted to the purpose, sew the whole upper together. For laced shoes the next operation is the placing of the eyelets, on an automatic 'eyeletting" ma chine, both sides mathematically correct at the same time. These 'eyelets' are of metal, with smooth, flanged top and a diminutive 'barrel,' which, during the operation, becomes clinched on the inner side of the shoe. This operation finished, the upper, completed, is sent to the 'bottoming," or assembling room, to be joined with the remaining parts of the shoe. In the meantime, in the sole room the outsole and the insole are roughly 'died out,* an operation sim ilar to the 'clicking,' or cutting, of the parts of the upper; then trimmed to exact size on a 'rounding' machine to the pattern of the sole. The outsole is then passed under heavypres sure through the 'rolling' machine, the fibres being compressed and the leather being made capable of greater wear. This is the old opera tion indifferently done on the shoemaker's lap stone by beating the leather. It is then put through a 'splitting' machine, for the sake of uniformity of thickness. The unit of measure is an 'iron'-48 'irons' being equal to 1 inch. The insole is treated in like manner, in addition to which, near the edge of what will be its eventual lower side, a slit of about one-half inch, extending toward its centre, is cut by a 'channelling" machine. At the base of the re sulting 'lip,' or flap, and nearer the centre of the insole a groove is cut during the same op eration. As will be seen later, the groove and slit are for the purpose of accommodating the stitching operation uniting the insole, upper and outsole. The 'lip' is now forced at right angles to the insole by a 'lip turning' machine, for the purpose of forming a lip, or shoulder, against which the welt is to be sewed, the groove on the inner side serving as a guide for sewing. Dur ing these operations the heel has been as sembled in another part of the sole room, the different pieces of leather, or 'lifts,' being cemented together and subjected to great pres sure. The 'counters' and "toe boxes,' respec tively the stiffeners for the shoe 'quarter' the part of the upper at the back and sides of the heel — and for the toe cap, are also made ready in the sole room. With the completion of all these, they are sent to the 'bottoming,' or assembling room.