700 



CAOUTCHOUC 



with the effect of cutting the tape throughout its length into eight or more threads at 

 once. An improved modification of that apparatus is described and figured in the 

 specification of Mr. Nickels's patent of October 1836. He employed it for cutting into 

 threads the tapes made from the recomposed caoutchouc. 



The body of the bottle of India-rubber, and in general any hollow cylinder of 

 caoutchouc, is cut into tapes, by being first forced upon a mandril of soft wood of such 

 dimensions as to keep it entirely distended. This mandril is then secured to the shaft 

 of a lathe, which has one end formed into a fine-threaded screw, that works in a fixed 

 nut, so as to traverse from right to left by its rotation. A circular disc of steel, kept 

 moist, revolves upon a shaft parallel to the preceding, at such a distance from it as to 

 cut through the caoutchouc, so that, by the traverse movement of the mandril shaft, 

 the hollow cylinder is cut spirally into a continuous fillet of a breadth equal to the 

 thickness of the side of the cylinder. Mr. Nickels has described two methods of 

 forming hollow cylinders of recomposed caoutchouc, for the purpose of being cut into 

 fillets by such a machine. 



It is probable that the threads formed from the best India-rubber bottles, as im- 

 ported from Para, are considerably stronger than those made from recomposed 

 caoutchouc, and therefore much better adapted for making Mr. Sievier's patent elastic 

 cordage. When, however, the kneading operation has been skilfully performed, 

 it is found that threads of the ground caoutchouc, as it is incorrectly called by the 

 workmen, answer as well for any ordinary purpose of elastic fabrics, and are, of course, 

 greatly more economical, from the much lower price of the material. 

 The following figs. 404, 405, 406, represent the machine for cutting the spiral 

 riband. The disc D, placed horizontally, turns round its vertical axis, so as to present 

 ts periphery to the edge of a knife c, formed like a circular blade, whose plane is 



404 



perpendicular to that of the bases of the disc. It is obvious, that if the disc alone 

 revolved, the motionless knife could act only by pressure, and would meet with an 

 enormous resistance. A third movement becomes necessary. In proportion as the 

 disc is diminished by the removal of the spiral band, the centre of this disc must 

 advance upon the knife in order that the riband may have always the same breadth. 

 The inspection of Jig. 406, will make the accordance of the three motions intelligible. 

 The knife c is placed upon a shaft or axis A, which carries a pulley, round which a 

 belt or cord runs which drives the whole machine. 



The shelf A bears a pinion p, which takes into a wheel H, placed upon a shaft A' ; 

 upon which there is cut a worm or endless screw, v v. This worm bears a nut E, 

 which advances as the screw turns, and carries with it a tie i, which in its turn pushes 

 the disc D, carried upon a shoulder, constantly towards the knife. This shoulder is 

 guided by two ears which slide in two grooves cut in the thickness of the table. The 

 diameter of the pinion p is about one fifth of that of the wheel R ; so that the arbour 

 A turns five times less quickly than the arbour A' ; and the fineness of the screw v 

 contributes further to slacken the movement of translation of the disc. 



The rotatory movement of the disc and its shoulder, is given by an endless screw 

 vr w, which governs a pinion p, provided with ton teeth, and carried by the shaft A, 

 upon which the shoulder is mounted. The arbour A' of this endless screw receives 

 its motion from the first shaft A, by means of the wheels s and s' mounted upon these 

 shafts and of an intermediate wheel s". This wheel, of a diameter equal to that of 

 the shaft A'', is intended merely to allow this shaft to recede from the shaft A. The 

 diameter of tho wheel of this last shaft is to that of the two others in the ratio of 

 10 to 8. 



