alterations, instances of which will be adduced. The driver has been still more simplified by applying it to the heel only of the shuttle, in place of at its front and back extremities; to the heel of the shuttle a projecting lip is attached forming a socket for the reception of the nose of the hammer-shaped reciprocating driver.

This arrangement cannot, however, be recommended, as it allows the point of the shuttle too much play in an upward direction. As unimportant variations, may be mentioned the construction of the driver for various sized shuttles, the imparting to it a slight return motion to allow of the loop slipping freely from the shuttle, as also by the application of a crank motion to propel the shuttle faster in its advance than its return, so as to shorten the dwell of the needle in its deepest position. To avoid the friction of the thread on the exterior surface of the shuttle, and the necessity of the needle standing still, by which the application of a crank motion is precluded, a moveable hook attached to the driver has been introduced, which catches the loop, and holding open allows of the passage of the shuttle without the thread of the latter coming in contact with the loop.. This may be considered as the transition to

it

SHUTTLES WITH FIXED SPOOLS.

The spool on which the thread, by which the loops of the upper thread are fastened, is wound, has in this arrangement only a revolving motion. A hook catches the loop and draws it over the spool. This hook, or looper, has either a reciprocating or rotating motion. The former is, however, but seldom employed owing to the complicated arrangements necessary, and develop

ments of the rotating looper appear to be the direction in which we must look for further improvements in the construction of sewing-machines.

The spool, Fig. 10, A B C, Plate VII, is so constructed that the thread of the loop slips easily and without friction over it, and owing to its answering the purpose of a shuttle it is not unfrequently so called. It consists of two halves brazed together formed of steel plate to

thick, well turned and polished, and the thread passes through the slit formed by the edges of the two halves. The slit is usually in., as this description of machine is mostly employed for fine work, and the edges must of course be rounded off so as to avoid fraying the thread. There are two requisites in the construction of the spool, viz. to allow as much interior space as possible, and to avoid too great a difference in the circumference of the thread when the spool is full and nearly empty. The spool is therefore generally made broader towards its axis, having generally 2"" as its greatest breadth, and the axis itself varies from

to of the diameter of the spool, which is between 14 to 15". To still further diminish the friction of the loop passing over the spool, the axis is sometimes sunk as in C, Fig. 10, Plate VII. The spool is contained in a hollow on the front side of the looper, so that the surface of the former exposed to view, q, Fig. 7, appears as a continuation of the front surface of the looper. The shape of this hollow, r s, is shown in the drawing. Between the hinder surface of the spool and that of the hollow is a space of in.

The needle having ascended in., the point of the looper rotating in the direction of the hands of a watch,

reaches the needle to in. above its eye, Fig. 22, A, and the needle continuing its ascent, the point penetrates still further the loop, Fig. 22, B, till the latter can slip no further on the projecting point, Fig. 22, C, and therefore falls into the groove, ef, Fig. 7, which runs round the periphery of the cylindrical surface of the looper, becoming narrower and shallower till it terminates in the vertical surface g. The farther the looper advances the longer the thread of the loop is extended in the groove, while the one side of the loop is compelled to slip behind the spool, and the advance being continued, Fig. 22, D, the thread conveyed by the groove reaches the above-mentioned vertical surface, and slips from it over the front surface of the spool. The loop has now reached a perpendicular position, Fig. 22, E, twisted diametrically round the spool, and would, the motion of the looper being continued, slip still farther to the left, passing over the spool, and at once quitting the looper, were it not for the so-called break acting against the circumference of the looper, Fig. 22, A, by which the loop is retained till the point of the looper has entered the fresh loop, Fig. 22, B, and there is no longer any fear of the old loop being again caught. The loop is freed from the break on the vertical surface of the looper reaching the latter, and leaving sufficient space for the thread to pass. The second point of the looper is only of secondary importance. A portion of the thread of the loop slips over its front surface, Fig. 22, E, when the loop commences to leave its perpendicular position and approaches the break, which being reached, the hinder thread of the loop slips off this second point, which is calculated to reach the needle at its deepest

point of descent. It is therefore evident that the looper must have travelled the distance of the two points from one another, while the needle has ascended to in. Their distance from one another will therefore be 3 in., if we reckon them to be 11 in. from the centre of the looper. If the diameter of the looper is in., it follows that the points are in. distant from the extreme periphery of the looper. The hinder surface of the

to

second point is also flat, but lies a little more forward than that of the first, so as to allow of sufficient space between it and the needle ( ́ ́ ́). This arrangement was first introduced by the Americans, Wheeler and Wilson, though not exactly as has been described, having undergone many modifications and improvements.

In some machines the spool has a reciprocating motion given to it in the direction of the axis of the looper, which is in this case hollow to allow of the passage of the spool.

II. THE MECHANICAL ARRANGEMENTS OF THE SEWING

MACHINE.

It has been shewn that all sewing-machines have a needle operating from above, and a contrivance below operating with it, the motion of each being dependent on that of the other. The mechanism by which the necessary motion is imparted to the needle is separated from that of the lower portion of the apparatus by the so-called sewing plate, containing the needle hole, through which the needle passes in its ascent and descent. The material to be sewn rests on the sewing plate, and is advanced the length of a stitch after the completion of each stitch by

means of the feed motion. There is also an arrangement for regulating the tension of the thread. Affixed to the sewing plate, at a distance varying from 3 to 12 in. from the needle hole, is a bent arm, or overhanging bracket, the head of which terminates above the needle hole and serves to support part of the mechanism. The height of the head from the needle hole varies from 1 to 5 in., but is generally above 3 in. A line drawn from the needle hole to the base of the arm is called the axis of the machine. Looking from the needle hole towards the base of the bracket are the right and left sides of the machine. The bracket is affixed to the hinder part of the machine, the needle hole is situated in the front.

THE MECHANISM FOR COMMUNICATING MOTION TO THE

NEEDLE.

The needle has an ascending and descending motion perpendicular to the sewing plate, and is affixed to the lower end of a shaft working in perpendicular guides, and called the needle carrier. To compensate for the wear by friction of the guide plates, the needle carrier shown in Plate VI., Figs. 1 and 2, TKP, allows of the plates being adjusted to it by means of a screw, the friction being also much lessened. The shape shown, Plate V., Fig. 10, is almost equally good, but is surpassed by that of Fig. 9, Plate IV. The one prism-shaped guide of the carrier is a fixture, while the other, admitting of a slight horizontal movement, can be tightened up by a screw when either the carrier or the guide has become