hook of the single-thread chain-stitch machine, and the revolving looper of the quilting-stitch machine, and those with a reciprocating or oscillating motion. These latter may be again divided into those with curvilinear and those with rectilinear motion. Those with a curvilinear motion describe either an arc with a very small angle, as the looper of the single-thread chainstitch machine, and the similarly constructed doublethread chain-stitch machine, or an arc with a larger angle, as in machines with travelling shuttles; or, lastly, almost a perfect circle, as the looper of the doublethread chain-stitch machine of Grover and Baker.

I. THE REVOLVING HOOK

is always attached to the end of the main shaft, which must therefore in this arrangement be below the sewing plate, and the mechanism for communicating motion to the needle must be arranged accordingly. (See machines shown, Plates II. and VII.)

II. THE HOOK WITH RECIPROCATING MOTION.

This hook makes, as previously described, a short motion from left to right, and then a still shorter lateral one; a pause occurs, and it then retraverses the same path. The motion from left to right and right to left is called the main motion, the other the side motion. The latter is effected in the following manner: The looper is affixed to a double-jointed lever swinging in a horizontal plane by means of a hinge, the axis of which is perpendicular. Lines drawn from the centre of the hinge to the point of the looper, and to the fulcrum of the lever, form an obtuse angle with its opening to the right. A spring, k, attached to the lever and

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pressing against a projection, h, of the looper (Plate I., Figs. 21 and 22), the so-called heel, endeavours to diminish this angle, but can only effect this in a limited degree on account of the pin i. The looper having concluded its motion from left to right, a part of it impinges on the pin m, and the lever continuing its motion, the point of the looper must move forward in the direction of the The side motion need therefore not be brought into consideration. The crank motion is inapplicable in this arrangement, and an eccentric groove must impart the necessary motion. The main motion must always be in the same direction as the movement of the material to be sewn, perpendicular to the axis of the machine. We have therefore only four arrangements to consider, according as the main shaft is above or below the sewing plate, parallel or perpendicular to the axis of the machine. By taking into consideration that the plane of oscillation of the looper might be perpendicular the number of arrangements might be increased to eight, but only the four following will be described:

The main shaft lies above the sewing plate, and parallel to the axis of the machine. The plane of oscillation of the looper is horizontal. At the rear end of the shaft is a disc with an eccentric slot, in which a roller rotates, attached to the end of a lever vibrating in a plane perpendicular to the axis of the machine. Plate VII., Fig. 35. The hinder end of the lower lever presses against the end of the lever vibrating horizontally. The roller therefore only comes in contact with the interior side of the eccentric groove, and a plate of an eccentric form is therefore frequently substituted. (See arrangement of machine in Plate I.)

The main shaft lies above the sewing plate, and perpendicular to the axis of the machine. The plane of oscillation of the looper is horizontal. A cylinder is attached to the shaft in which is the groove. The hinder end of the lower lever is turned upwards, and supports on a vertical pin the roller running in the groove perpendicularly below the main shaft. (Plate VII., Fig. 36.)

The main shaft lies below the sewing plate perpendicular to the axis of the machine. The plane of oscillation of the looper is horizontal. This arrangement differs but little from the preceding ones, except that the end of the lever need not be turned up.

The main shaft lies below the sewing-plate, parallel with the axis of the machine. The plane of oscillation of the looper is perpendicular. The disc with the eccentric slot is attached to the end of the shaft and the roller between the looper and the pivot of the lever, Fig. 37. If, however, it is intended to give the vibrating motion to the groove, the roller is attached to a crank plate on the main shaft, Fig. 38.

3. SHUTTLES WITH CURVILINEAR OSCILLATING MOTION. The shuttle is situated at the end of a lever describing in its motion an angle of generally 45 to 60 deg., but seldom exceeding 90 deg. The lever vibrates either in a vertical or horizontal plane, and the chord of the arc described can be parallel or perpendicular to the axis of the machine, of course always in a horizontal plane. the main shaft can also be parallel or perpendicular to the axis of the machine, the position of the chord of the arc to the main shaft must be either parallel or perpendicular. Taking into account that the shaft can

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As

either be above or below the sewing-plate, and that the motion can be imparted either by a crank or eccentric groove, sixteen different variations can occur, the principal of which are described below.

The plane of oscillation is horizontal, the main shaft lies below the sewing-plate, parallel to the chord of the arc of oscillation, and motion is transmitted by means of an eccentric groove. The groove is situated either on the plane surface of a disc on the main shaft, Plate VII., Fig. 39., or on the circumference of a cylinder attached to the shaft, Fig. 40. In both cases a two-armed lever transmits the motion by means of a connecting rod to another two-armed lever which is straight when the groove is in a disc, and bent when the groove is in a cylinder.

The plane of oscillation is horizontal, the main shaft lies above the sewing-plate perpendicular to the chord of the arc of oscillation, and motion is transmitted by an eccentric groove. A two-armed straight lever transmits the motion from the eccentric grove, by means of a connectingrod, to a second lever actuating the shuttle. This latter lever is single when the grove is in a disc and the main shaft is perpendicular to the axis of the machine, Fig. 41. It is two-armed and bent when the groove is in a cylinder, and the shaft runs parallel to the axis of the machine, Fig. 43. If the groove is in a cylinder and the shaft perpendicular to the axis of the machine, the lever assumes dimensions presenting considerable difficulty.

The plane of oscillation is horizontal, the main shaft below the sewing plate, parallel to the chord of the arc of oscillation, and motion is transmitted by a crank. The shuttle is situated on the long arm of a bent lever, the short

arm of which is joined to the crank by a connectingrod. As the crank is very short a simple crank-pin would be sufficient, lever and connecting-rod being joined by a universal joint, Fig. 44.

The plane of oscillation is horizontal, the main shaft below the sewing-plate parallel to the chord of the arc of oscillation and motion is transmitted by an eccentric groove. This combination allows of the very simple arrangement shown in Figs. 45 and 46, the latter of which is particularly applicable when the shaft is parallel to the axis of the machine.

The plane of oscillation is horizontal, the main shaft below the sewing-plate perpendicular to the chord of the arc of oscillation and motion is transmitted by a crank. The shuttle is placed at the end of a straight two-armed lever, the short arm of which is attached to the crank by means of a connecting-rod, both ends of which are fitted with universal joints, except when it is very long, when a simple cylindrical crank-pin will be sufficient, Fig. 47.

The plane of oscillation is horizontal, the main shaft below the sewing-plate perpendicular to the chord of the arc of oscillation and motion is transmitted by an eccentric groove. The shuttle is situated at the end of the longest arm of a bent lever to the other arm of which the roller is attached, running in the groove of a cylinder, Fig. 48. See also arrangement of machine, Plate V., Figs. 20 and

21.

The plane of oscillation is perpendicular, the main shaft above the sewing-plate parallel to the chord of the arc of oscillation and motion is transmitted by a crank. The lever carrying the shuttle is attached to a horizontal shaft