perfection of mechanical sewing necessarily depends on the stitches produced in the seam of the fabrics to be connected. The different inventions patented in the United States are capable of forming upward of sixty-five distinct stitches, employing front one to three threads. These, however, may be reduced to three varieties—namely, the simple chain- or crochet-stitch, the double chain-stitch, and the lock-stitch. The Last-named is the most popular of these stitches and requires the smallest amount of' thread.
earliest attempts to produce a seam me chanically were in imitation of hand-sewing. In 1755, Charles F. Weisen thal devised a double-pointed needle with a central eye (pi. 53, fig. 2) for the production of the ordinary basting-stitch made by hand. In this contrivance the needle was pushed throng]] the material, then guided through the stuff in another place in the opposite direction, being alter nately caught by two nippers, one on each side of the piece to be united. This mode of operating is now utilized in Heilmann's embroidery-machine, winch will be considered farther on. By another method the needle pen etrated several convolutions of the undulated material (fig. 3). For producing the latter form of basting seam Figures 7 and S exhibit two machines which are much used in finishing- and print-works for stitching together the ends of separate pieces of goods. Two cog-wheels gearing into each other catch and gather the fabric into many regular folds, which are pushed upon a long threaded needle. The needle is fastened to the frame and can be brought close to the gear-wheels by means of a groove in their peripheries. By detaching the needle from the frame and draw ing it completely through the folds the thread is drawn after it, and the united ends of the stuff are then straightened.
Single Chain-stitch.—Figures 2 and 3 (ft/. 54) give an accurate illustration of the single chain-stitch. Each stitch of the,thread forms a loop, which encloses the loop of the succeeding stitch. By pulling the thread on one end (to the right in fig. 3) a very easy separation of the two layers of stuff is possible (fig. 2)—a result that is desirable in some cases of domestic pur poses, but that is objectionable as regards durability. The ordinary method of forming this stitch by a revolving hook is shown in Figure 12 (fii. 53). At a is seen the formation of a loop, caused by the descent and the beginning of the return-stroke of the needle, which has on one side a shallow groove, so that in withdrawing the thread is retained in the stuff by the friction, and thus forms a loop. Into this loop the point of the hook, which rotates
on a horizontal axis, catches, and during its subsequent rotation of 180° the needle retrogrades entirely, the loop is completely drawn over the hook, and the material is simultaneously pushed forward the length of the stitch. The loop formed has then the shape represented by c, which remains for a moment so far open that the succeeding descent of the needle passes through it. With the completion of the revolution of the hook the loop leaves the latter and encloses the new loop made by the entering point of the hook, the intertwining of the thread thus effected producing the so-called " open-mesh " stitch in crocheting. This method of forming the single chain-stitch seam is peculiar to the Willcox & Gibbs machine (fig- 6).
Figure 9 exhibits a single chain-stitch machine in which an oscil lating hook or needle and a feeder are made of a single strip of sheet metal. The needle is an attenuated extension of the metal strip, which is bent back on itself and forms an elastic spring. The feeder is formed by a lateral projecting strip with a forked end, which is bent over, so as to produce a spring-like curvature with its forked end resting on the main piece. Holes are drilled in the needle-holder and in the needle-point, through which the thread is rove. On pressing the needle-holder down the needle is pushed through the cloth; the needle, on rising, leaves a loop on the under side of the cloth, and the feeder, having been forced back by the needle in its downward passage, advances and moves the cloth and the loop along for the succeeding stitch. The next time the needle comes down it passes through the loop just formed, and so on con tinuously. The practical availability of such a simple machine unfortu nately ceases at a certain point.
Double the double or two-thread chain-stitch the upper thread in each stitch forming the loop is drawn completely through the cloth, and is secured on the lower side by a second thread, which not only encompasses the loop, but also penetrates it (/5l. 54, figs. 6, 7). This stitch, which is original with the patentees, Grover S Baker, gives a very durable scam, and by using an especially heavy lower thread a beautiful ornamental stitch. The production of the double chain-stitch, however, requires the greatest amount of thread.