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LARGER IMAGE]

The selection of racks and cams is made by pattern cards (detached) which pass over an octagonal prism, N. The cards are presented separately, once in two picks, to three selecting needles, 1, 2, 3. The two outer needles, 1, 3, are attached one at each end of a double arm secured at the top of a long vertical shaft, O, the bottom of which communicates with the forked rack G. Thus a depression of boxes is effected by a blank part of a card pressing against needle 1, and an elevation of boxes by pressing back needle 3. Shaft O is loosely contained within a long tube or sleeve, P, which carries a short arm, R, at the top, and a forked clutch, Q, which acts upon the boss of cams, B and C. If it is desired to move two boxes, needle 2 is pressed back, thereby causing an inclined piece, S, secured to it, to act upon arm R so as to slightly turn the sleeve P, and move the larger cam C under the treadle bowl at a time when the short side of the cam is uppermost, as indicated in the diagram, [Fig. 77]. At one point, the larger and outer cam is slightly lower than the smaller one, and can be readily moved under the bowl.

The various changes which can be made by this motion may be seen by referring to the cards at [Fig. 77]. When there is a blank opposite the first needle only, the rack H′ is pushed to the left and the boxes are moved “down one.” When there is a blank opposite the third needle only, rack H is moved to the right and the boxes are forced “up one.” When there are blanks opposite the first and second needles, they are pushed backward, thus moving rack H′ to the left, and also forcing the larger cam under the treadle bowl, in which case the boxes will be moved “down two.” When there are blanks opposite the second and third needles, they are pushed backward, and the boxes are “raised two.” When there are three holes in the card, the racks, when lifted, miss the wheel, and there is “no change” in the boxes. It will be seen that the boxes may be moved either up or down, a space of one or two boxes only at a time. There may be more than three boxes, as many as five being regularly used; but if there were five, it would not be possible to change from the first box to the fourth or fifth. The greatest change which can be made is from the first to the third, fourth to second, and so on.

WHITESMITH’S DROP-BOX.

The principle of Whitesmith’s motion is probably the best for any number of boxes. It is usually made for four, and the change may be made with certainty from one box to any other. The arrangement for working four boxes in a loom is illustrated at Figs. [78], [79], [80]. The principle will be best understood by referring first to [Fig. 80]. The four different positions of the boxes are here shown. The boxes are connected to the ring or strap of an eccentric at the point E, and at A the position of the parts is shown when the boxes are at their lowest point. The eccentric, F, on the shaft has a lift of one box, and therefore by causing it to make half a revolution intermittently every two picks, the boxes would be alternately lifted and dropped a space of one box, as will be seen by referring to C ([Fig. 80]), where it has made half a revolution from its position at A. It will be seen that E is one box higher at C than at A. Starting again from the first position, as at A, by turning the outer ring halfway round and leaving the eccentric stationary, there will be a lift of two boxes. This is shown at B ([Fig. 80]). Again starting with the first position, as at A, if we turn the outer ring halfway round, and at the same time turn the eccentric F half-round, we lift a space of three boxes—that is, from the first to the fourth box. The position of E in this case is shown at D ([Fig. 80]). We thus see how from the bottom box any other of the four can be reached. By turning the eccentric halfway we lift one box, by turning the ring halfway round we lift two boxes, and by turning both ring and eccentric halfway round we lift three boxes. If we are at the third box, as at B ([Fig. 80]), and we wish to reach the second box or one lower, by turning the eccentric half a revolution and the ring half a revolution we shall get the position required. It will thus be seen that any one of the four boxes may be reached at will. At [Fig. 79] another view of the eccentrics and boxes is given. The wheel H is keyed to the shaft on which the eccentric is fixed, and riding loosely upon this shaft is another wheel, I, of the same size, to which a fork, K, is attached. This fork fits on to a pin at the back of the ring, and thus by turning the wheel I the ring can be moved independently of the eccentric. If the wheel H is moved it moves the cam, and if the wheel I is moved it moves the ring. Referring now to [Fig. 78], the wheel H is shown. This wheel is driven by a wheel, I ([Fig. 79]), twice its size. On the face of the wheel L there are four pins, and by lifting the lever OP at O, the pulling hook M is dropped round one of the pins, and the hook being moved forward by the crank Q will cause the wheel L to make a quarter of a revolution and the wheel H to make half a revolution, and therefore the eccentric is moved half a revolution. On the same stud as the wheel L there is another wheel exactly the same size and with four pins; this wheel (which cannot well be shown in the diagram) gears into the wheel I shown in [Fig. 79]. There is also another pulling hook which works along with M. This second pulling hook is operated by another lever like OP. There are two levers, X, which are lifted by the cards, and by lifting X, either, or both, of the pulling hooks may be dropped, and either of the wheels I or H ([Fig. 79]) turned half a revolution, but always in the same direction.

FIG. 78.

FIG. 79.