The & Baker Afachine was invented in 1851 by William O. Grover and William E. Baker, and was patented in 1852. It employed two reciprocating needles. The upper or vertical one was a straight eye-pointed needle, which passed through the material and made a loop, through which the lower curved and eye-pointed needle passed horizon tally, forming a second loop, the needles so operating as to interlock the two loops, thus making the double-looped stitch, which, though elastic and strong, was objectionable on account of the ridge left on the inter lacing side of the cloth. Later the machine was somewhat modified: the vertical needle was curved and was carried by a vibrating arm, and the looper or lower needle was made to operate by the special mechanism now common in the machine.
& Gibbs 1856, James E. A. Gibbs, a Virginia farmer, devised an improved chain-stitch machine which, under the sub sequent patents of C. H. Willcox and others, is popularly known as the Willcox Gibbs sewing-machine (pl. 53, fig. 6). It employs the eye pointed needle and an ingenious rotating hook, which revolves beneath the cloth-plate. The needle is carried by a reciprocating bar actuated by a vibrating lever connected by a link with an eccentric on the main shaft. As it rotates, the hook, which is at the forward end of the main shaft, catches the loop of the needle-thread, expands it, and holds it expanded while the feed moves the cloth. When the needle descends through the first loop, the point of the hook is again in position to catch the second loop, at which time the first loop is cast off and the second is drawn through it, the first loop being drawn up against the under surface of the cloth, thus forming a chain-stitch. Subsidiary devices are attached for regulating the thread-delivery, the feed, the tension, etc.
and —Figure i6 (pi. 54) represents a sew ing-machine with which is combined the important feature of a buttonhole machine without the use of attachments or complicated mechanism. The combination is so effected that neither branch of work interferes with the other. It is adapted to use one or two needles and will make at one opera tion two seams, either straight or zigzag (fig. S), the latter seam being produced by the same device that is employed in making the buttonhole stitch (fig. 8).
employ either straight or curved eye pointed needles. The straight needle, which is fixed in a vertical bar and reciprocates in a straight path (fig. i), is the least likely to bend or spring when in operation, in which respect it has the advantage over the curved needle, and must ultimately take the place of the latter. The curved needle oscillates on an axis, and it must be so set that its curve shall exactly coincide with the arc in which it moves, otherwise it will draw the material, and in crossing seams be liable to spring and to break.
Sluallc and Rotary Hook. —Externally the ordinary sewing-machine shuttle is shaped, approximately, like the half of a cigar cut lengthwise, with a cavity in its flat side for the bobbin containing the lower thread (pl. 53, Jig. i6). Of this form of shuttle there are various modifications. The shuttle rests in a guide-way or track, called a "shuttle-race," into which the needle descends, so that the point of the shuttle may enter the loop of the needle-thread. At first the race-way lay parallel with the line of time scam, but in the Blodgett-Lerow patent the race-way was circular, and in later forms it is at right angles to the feed, by which the transverse reciprocation of the shuttle greatly improves the evenness of the seam. Various contrivances have been devised for driving the shuttle in the race, but the preferred forum of mechanism is the shuttle-cradle or car rier, which is shaped to receive the shuttle within it and to move with and pass the shuttle through the loop of the needle-thread. An improved device for passing the lower thread through the needle-thread loop is it rotating hook which is so bevelled and notched as to seize the loop, expand it, and pass it. around a stationary discoidal bobbin containing the under thread (pi. 53, 13, 14). Intermediate between the shuttle and the rotary hook is the Singer oscillating shuttle (fix-. 15). The latter is hook-shaped, similar to the preceding, and carries within it a circular bob bin. The shuttle is driven by an oscillating driver in an annular race way, but, instead of revolving completely, it is moved in an arc of only 15o°, or so far as serves to catch and clear the upper thread.
• moving the material intermittingly past the needle there have been employed various devices, most of which, in describing the development of the sewing-machine, have been noticed in the preceding pages. In popular makes of machines the feeding mechanism is for the most part of the " four-motion" class, in which a notched bar rises against the cloth, moves it forward horizontally the length of a stitch, falls, and returns to its original position. The direction of feed may be either in a line parallel with the eye of the needle or at right angles to it. In the latter method the thread, after passing through the eye of the needle, is turned about the needle, which produces more friction upon the thread than the first plan.