CHAINWORK. 



715 



Tambour- largest traverse wheel. Upon the large spin-lie the 

 in^. j,,,j,\ -rips a small band passing two or three 



v '-.'' times round it, and from each end of which is sus- 

 pended a weight. That represented at N is much 

 heavier than the one suspended from the opposite 

 side, as its intention is to pull in a direction contrary 

 to that of the impelling power. This excess of 

 weight must be sufficient to pull back the band by 

 friction, after the pulley has been stopped by the 

 spring catch 1 laying hold of one of the notches in 

 the ratchet K. The effect of this apparatus is as 

 follows. When the main spindle O has performed a 

 revolution, or somewhat more, by the descent of the 

 rack D, any excess is instantly cured by the joint 

 operation of the balance-weight N, and the friction of 

 the rack D in reascending ; and the position of the 

 tooth in the ratchet K becomes the stop by which the 

 relative positions of the feeding and working needles 

 are preserved. Merely for the sake of conveniency, 

 the calculation between the front rack for the needles 

 and the back rack for moving the regulator K, was 

 taken as two to one. Both derive their motion from 

 the inverted levers KK, (Fig. l.)j; and hence the 

 range of one will always be proportional to that of 

 the other. When the inverted levers are shifted either 

 way, the needles before, and the regulating ratchet 

 behind, change positions by the same power, and at 

 the same instant. The perpendicular rack gives al- 

 ways more than a full revolution to the feeding crank, 

 but the excess is instantly corrected by the action of 

 the counterpoise N, and thus the relative position of 

 the two frames is uniformly and correctly preserved. 

 When the motion of shift is in the contrary direction, 

 the spindle O is carried with the rest of the appara- 

 tus, to which the moving wheel C, being loose, pre- 

 sents no obstruction. 



Of the operation of that part which produces 

 I. the second, or reciprocating motion of the feed- 

 Fig. 3, 4. ing-bar, the most correct idea will be formed by 

 referring to Figures 3. and 4. In Fig. 3, a pro- 

 file elevation of it is given, in which almost every 

 part may be distinctly seen. Let A represent a 

 cro^s section of the beam which carries the whole 

 fetding apparatus. From this beam descends two 

 projecting arms ; one of which appears at B, and the 

 other is in every respect similar. Their horizontal 

 appearance appears behind R, in Fig. 4-. Between 

 these arms is a cross shaft, placed so as to vibrate 

 freely in the centres ; and at each end the perpendi- 

 cular arms are joined by the cross shaft, the arms be- 

 ing fast upon the shaft. From the middle of the 

 shaft, the lever E projects at right angles to the 

 arms, and at the extremity is fixed a weight, in order 

 to give it a tendency to descend ; by which descent 

 the perpendicular arms are impelled forward towards 

 the cloth. From the upper part of the perpendicu- 

 lar arms, a connection is formed with the back part 

 of the feeding bar, by means of two wires, with a 

 hook or eye-joint at each end, to prevent them from 

 impeding the circular motion of the bar. When the 

 level E is at liberty, thr weight descends, and the 

 feeders spring forward close to the cloth. When the 

 perpendicular shaft which carries thi rack of the feed- 

 ing machinery (D. Pate CXXXVI Fig. 6.) re- 

 ascends, a jointer! catch, represented at F, catches the 

 proj. -cling arn; E, lifts it up, and produces the retro- 

 grade motion of the k-eiin. . n . edict, in order to pull the 



threads close into the barbs of the working needle*. Tambur; 

 When the working needles are bhut, and leaving the ">' 

 cloth, a small hammer, fixed to the back wooden N *~Y^*^ 

 roller, by striking a crank, forces back the catch; 

 and the projecting arm descending, brings the 

 feeding needles again close to the cloth. Thus the 

 reciprocating motion is communicated to the feeding 

 bar. The form of the crank at O it useful for thi* 

 motion, because it tends, when the bar recedes, to 

 bring back the threads much more fully into the 

 barbs of the working needles, than a rectangular 

 crank, where much of the obliquity would stm be 

 pre.erved, could effect. In the first experiments, 

 cranks of the common kind, and similar in appear- 

 ance to what is represented by the lower dotted 

 lines, were employed, and afterwards abandoned for 

 this special reason, and after their inefficiency had 

 become apparent from actual experience. 



The chief parts of this complicated machine being 

 now described, at a length as great as the limits of 

 our work can admit, and perhaps tiresome to some 

 readers, the mechanical description shall be conclu- 

 ded with some remarks upon that part of the ma- 

 chine, which is, of all others, that which requires the 

 greatest portion of attention, and upon the accuracy 

 of which the chief, if not the only difficulty, in ac- 

 tual practice was found. This lies in the construc- 

 tion of the needle, and apparatus belonging to it ; 

 and what illustration can be given by representation, 

 without a great multiplication of figures, will be PLAT* 

 found in Figure 2. CXXXVll. 



The tambouring bears so strong an analogy to the Fig. 2. 

 stocking manufacture in the chaining, that at first 

 the experiments were made with needles in every re- 

 spect similar to those of the stocking frame, that is 

 to say, with bent pieces of iron-wire, shut by the 

 pressure of an iron bar, and re-opened by their own 

 spring or elasticity. A very few trials proved this 

 to be inapplicable to tambouring, for three reasons : 

 The first of these was, that, by bending the wire, 

 the flexure, which really formed the point of the 

 needle, was too blunt to perforate the cloth, without 

 risk of injury to the fabric ; and the metal was too 

 weak to bear sharpening after the flexure was made. 

 The second was, that the pressure of the bar which 

 shut the barbs, also made the stems yield very con- 

 siderably, and this was apt to injure the cloth. The 

 third reason was, that, in order to present the barbs 

 to the action of the pressing bar, the needles requi- 

 red constantly to be brougTit back from the posi- 

 tion necessary for the pattern, to one where the 

 barbs would be vertically over the stems. In order 

 to remove all these objections, a principle was adopt- 

 ed, by which all those objections were removed. The 

 hook, or needle, was manufactured from solid wire. 

 The barb was made very short, like that represented 

 in the figure. The closing of the barb was effected 

 by a small slider belonging to each needle, and the 

 pressing bar entirely removed. The barb of the 

 needle was cut like those of common fishing hooks ; 

 and, like them, the needles were made from steel 

 wire, so as to be susceptible of tempering. Thi.- af- 

 forded a facility of sharpening the points, as much 

 as those of sewing needles, and removed the other 

 objections, as they could now be opened and s/.ut 

 in any position. In this improved state, their 

 appearance will be found very much such as in 



