For the purpose of allowing the cutter to come fairly in contact with every part of the circumference of the spiral traverses ; while the pattern is cutting, it will be proper to construct them in pieces equal to one revolu tion of the spiral, and these pieces may be removed while cutting, and when the cutting is finished, all may be placed on the axis, and secured by screws, or any other sufficient fixture. In order to allow the friction wheels, which are in contact with the rims of the spiral, to traverse freely along, some such contrivance as that represented in Figure 10, may be adopted. To the lower extremity of each lever may be fixed a small bow or brace of iron, at right angles to the lever, and secured by a screw at D. Two cross shafts, one immediately above the other, may be fitted to slide freely in the brace from side to side. To each of these a small friction wheel may be fitted, with a groove in the rim, to lay hold upon the circumference of each spiral. When the spirals revolve, the friction wheels, by the action of the hollow grooves, will be drawn laterally along them from F towards E; and when they have completed their course, they may be drawn back by a weight or spring, whenever the groove in the friction wheel is removed from the circumference of the spiral. The perpendicu lar motion of the cloth frame will be very apparent in the elevation, Fig. 2. ; for the action of the spiral upon the lever L will produce it, by means of the cords 00, passing over the puhies in the cross rail N. If these cords are double, and joined in the middle by the slip knot used by weavers for the cordage of looms, the frame may be tempered to remove any inaccuracy aris ing from stretching, with great promptitude and facility. The horizontal motion may be given to the cloth frame by a direct connection with the other spiral, as in the former machine.
This will perhaps he the most simple and efficacious mode of giving the traverse motion, where a single row of perforators only is to be used ; but as it may be desira ble to increase the quantity of work by using different rows of perforators at the same time, and as no insur mountable objection presents itself against this amplifi ration of principle, it may now be proper to extend our views to the means of augmenting the scope of the machine, premising that the ratio of increment can never be so well ascertained or productive of actual benefit, as by practical experience. lf, in the first instance, we propose to double the number of our perforators, so as to work two rows of figures but inverted, we may adopt the machinery reprelamted in Figure I 1, with rational hopes of complete success. But here it will be evident, that from the very nature of our object, we must abandon the plan of giving the lateral or horizontal shift to the cloth, and communicate it to the perforators, as they must now work in inverted directions. It will also be necessary that the vertical needles, which secure 1.1io loops in front, must move along with the perforators, and that this must be done with great accuracy. In
this case, therefore, the vertical motion may still be given to the cloth, but the lateral one must be com municated to the perforators. In Fig. 11. if a motion is given to the frame AB, by the action of a spiral tra verse upon the lever A, the frame CD will operate con stantly in an inverted direction, by means of the pulley and band at G. The upper frame being acted upon by the traverse, is kept pressing upon it by the operation of the weight F, and the lower frame works in constant opposition to it by that of the minor weight E, which preserves the tension of the connecting band at G. If four frames he wanted, the plan in Fig. 12. will effect it The motion of the middle frames 2 and 3, is exactly as before, and the motion is continued to the upper and lower frames by the cross clasps at H and I. A profile of these clasps is given in the small Figure 13. In using an apparatus so extensive as this, it will be necessary to devise means, either by hinges or otherwise, for speedily removing and replacing the upper frames, so that all may be accessible for the purposes of repair or regulation, without loss of time.
It will now be proper to advert to the means of pre. serving the relative position of the vertical needies in front to the perforators, and for this reference may be made to Fig. 14. Let the cross rail in front of the cloth, which is to support the needles which retain the loops, be constructed with a groove nearest to the cloth, into which a small wedge may be driven for each needle, as represented at A. Let the needle be cast into a socket of tin, of the form represented at B, and a small weight be attached to the oblique tail at C. In the side of this needle let a groove be punched, like that of a common stocking needle. At B must also be a socket upon which the tin may vibrate freely from side to side, and the gravity of the oblique weight at C will give the point a constant tendency to incline towards the left hand. The point rising through a groove in the frame at 0, its posi tion may be regulated with the utmost precision, by tempering the wedge at A, and thus it will be made to fit the perforator with very great nicety. The rising of this needle between the perforator and thread, will thus seize every loop ; and the next consideration is to open these loops, so that the perforator may pass fairly through them at next perforation, without danger of missing. This, it is presumed, may easily be effected with great safety, and little danger of error, by the fol lowing addition to the apparatus. Upon the same centre at B, let there be a second needle, shorter than the for mer, and also fitted with an oblique tail to incline its point towards the left. The point of this short needle 1), resting in the groove of the longer needle 0, both will rise as one point, and any slight motion to distend them afi yr being raised, will open a loop through which the perforator may pass with the utmost security at the perforation.