each other upon the barrel. When the traverse is completed, the movement of the rail is reversed, and at the same moment the speed of the bobbin is accelerated, and a second layer is laid upon the first; the bobbin, if before ascending, now descending, or contrariwise. After the second layer is completed the bobbin again turns back, receiving at the same instant a further acceleration of speed. This takes place at the completion of every layer. With the increasing diameter of the bobbin a fewer number of turns are required to take up the rove delivered. This enables the lift or traverse to be diminished by about the amount of one coil per traverse, and as this diminution takes place at both ends, the effect is that the rove at the extremities of the bobbin is built upon it in the form of cones, the lower one of which is inverted, as will be seen from Fig. 44, in which two bobbins are shown upon the spindles, one being empty, and the other full. It may be necessary to observe that the arrangement here described of the differential motion, and its application to both the speed of the bobbin and the lifting of the traverse rail, necessitates the uniform filling of one " side" of bobbins at a time, and a similar order of doffing; not permitting, as in the flyer spinning frame, the doffing of one bobbin at a time if it is thought desirable.

The spindles of the slubbing, the intermediate, and the roving frame are constructed alike, and with only slight variations in detail by the different makers. The following Fig. 44, exhibits a detailed view. The spindles, a a', are mounted in the frame as shown, one behind the other, and are driven by the shafts, bb', by means of the bevelled gearing, c c'. The flyers, d, are securely mounted upon the spindle tops at e, so as to partake of their rotatory motion. The flyer consists of a tube, f, and two hollow legs, hh, to which the pressure fingers, ii, are affixed at kk'. The latter turn freely on their bearings at k, the pressure upon the bobbin being induced by the quick rotation of the spindle and the resistance of the air against

the bobbin. The slubbing, after being delivered by the rollers, is conducted into the tube of the flyer at 1, and comes out of it at m; it then enters one of the tubular legs at n, from which it emerges at p, when it is coiled several times round the presser, i, which assists to consolidate it, and then passes through the hole, i, upon the

bobbin, r. The bobbins receive their motion from similar shafts, ss', and gearing, tt', to those of the spindles. As the two shafts driving the spindles of the front and back row are actuated by a common driver, they necessarily revolve in opposite directions; in order, therefore, to secure the revolution of both lines of spindles in one way, one row is placed to the left and the other to the right of the driving

shafts. A similar arrangement prevails with regard to the driving of the bobbins, as will be seen from Fig. 44.

These complex yet harmonious movements are produced by some very ingenious mechanical arrangements which now require description. The following illustrations, representing the mechanism of a roving frame in the order of its parts, will be of assistance to a thorough comprehension of its structure and working. Being different presentations of the same mechanism, the respective parts, as they appear in each drawing, are marked with the same reference letters.

The driving shaft, a, Figs. 45 and 46, is usually fitted with 12 in. fast and loose pulleys. A wheel, a, upon this shaft works into a carrier wheel, a 1, which actuates another wheel, a 2, upon, and by which, the spindle shaft, B, is driven. This wheel gears into a similar wheel, a 3, upon the spindle shaft, B1, which being of the same size, both shafts revolve at the same speed. These shafts, B, в 1, carry the bevel gearing driving the spindles, and which has been previously described.

The shaft, A, first mentioned, also carries a pinion, b, Fig. 45, working into a carrier wheel, b 1, which again actuates another wheel, b 2, on the shaft, c, of the driving cone. Upon the latter shaft there is a wheel, c, gearing into a second, c 1, actuating the front roller shaft, D. A pinion, c 2, Fig. 47, upon this shaft drives a wheel, c 3, on the axis of which is a pinion, c 4, gearing into another wheel, c 5, which drives the back roller, D 2. Upon the back roller is a pinion, c 6, actuating a carrier wheel, c 7, driving a pinion, c 8, upon the centre roller, D 1.

As remarked before, the arrangement of the rollers is such that only a very small draught occurs between the back and middle roller, nearly the whole of the latter occurring between the middle and the front rollers. The rollers are usually set by means of a gauge, the distance from centre to centre of the front and back roller being such as not to exceed, or fall short of the length of staple

of the cotton in use. The three bottom rollers are fluted, and also the top back roller, but the middle and front top rollers are covered with leather. The top rollers rest upon the bottom ones, and are moved by contact with the latter. This is preserved by means of weights suspended on hooks.

The differential driving of the bobbins yet remains to be explained. The shaft, A, besides the wheel, a, driving the spindles through the train of gearing as described, carries

a second wheel, e, which is shown broken upon the shaft, a, in Fig. 45, and more distinctly, but without its connected train, in Fig. 46. The bobbins receive their motion from this wheel, the revolutions of which are required to increase by a constant number, as each added layer of rove enlarges the diameter of the bobbin. This acceleration of the revolution of this wheel is produced by a cone driving-motion connected with a differential wheel-motion, commonly called a "jack in the box" motion. The cone, T 1, is driven by a

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