832 



WEAVING. 



suffer the least possible strain by the motions of 

 weaving. The beams should be parallel, true, 

 and placed very nearly on the same horizontal 

 (lane. The stretch between the two beams 

 should not be longer in power looms than to 

 give a sufficient spring to the yarn in forming 

 the shed. As the shed is much bigger in coarse 

 than in line work, the length of the stretch should 

 vary accordingly. It is of great importance in 

 weaving fine work, to have a short stretch. 

 Hand-looms have invariably too long u stretch; 

 and power looms generally too short. There 

 is a want of adaptation in both cases, arising 

 from opposite reasons. To get as many looms 

 as possible in his factory, the manufacturer by 

 pouvr diminishes his stretch without perhaps 

 being aware of the disadvantage. The hand- 

 loom weaver increases his stretch to get as much 

 yarn as possible dressed at a time. The power 

 loom weaver's yarn, therefore, snaps suddenly from 

 insufficient spring when a knot in the thread 

 comes in contact with the reed. In hand weaving 

 the yarn gives way by the strain it sustain! in the 

 length of the stretch. Moreover, to keep the 

 yarn sufficiently tight, heavy pacing is necessary, 

 and this greatly increases the evil. 



The next consideration is to save the yarn, by 

 dispensing with all excessive and harsh motion. Of 

 all the motions of weaving, the shedding of the 

 web is the most severe on the yarn. This motion 

 therefore should be perfectly smooth ; and the 

 shed sunk no deeper than will barely admit the 

 shuttle. Three rods are put in behind the hed- 

 dles to keep the yarn firm, and preserve the 

 lease. The first two preserve the plain shed, and 

 the third, which is properly the lease-rod is put in 

 to a shed formed with two threads above, and two 

 below the rod all over, for the purpose of binding 

 the yarn still more together. These rods should 

 be placed as for behind the heddles as the heddles 

 are from the fell, but no further. 



The motion of the lathe in power looms is 

 very often bad. The best arrangement for this 

 purpose is to hang the lathe like a pendulum,, after 

 the manner of the hand loom weavers. And to fit 

 the lathe for working well at any speed, the length 

 of the swords, or the radius of the arc which the 

 lathe describes, should be increased or diminished 

 accordingly. For narrow work with a great speed, 

 the swords should be shortened, and lengthened 

 for broad work where the speed must be dimin- 

 ished. In power loom weaving, this position of 

 the lathe is usually reversed ; it is generally placed 

 inverted with its centre of motion below the web. 

 The only advantage arising from this arrange- 

 ment, is that it renders the loom more compact 

 than it would be by the hanging lathe ; and the 

 motion, although not really so good, cannot be 

 called injurious to the coarse work, for which 

 the loom is fitted. In other power looms, such as 

 the one last described, the lathe is without swords, 

 and slides backward and forward on two guide 

 rods. This motion, however, is so far objection- 

 able, as it wants firmness and smoothness. For, 

 let the guide rods be ever so well fitted, they must 

 have some play, which will increase by wear, and 

 therefore the lathe must suffer much snaking from 

 this cause, independent of its inability from position, 

 unsupported by leverage, to withstand the shock of 

 the fell. The lathe in the eccentric power loom 

 has swords in the usual manner, and motion is com- 

 municated to it by an eccentric spur wheel and 



pinion instead of the common crank. This motion 

 was invented and patented by Mr Archibald Buch- 

 anan of Catrine, in Ayrshire ; but had also been in- 

 vented some years before Mr Buchanan, by a me- 

 chanic of Glasgow, and used in the north of Scot- 

 hind for the weaving of sailcloth. It will be ob- 

 served, that the motion communicated to the 

 lathe by the connecting rod from the crank, li;>s 

 a pause in turning the centre at each side, ot 

 nearly equal duration. Now this is not the 

 motion that the weaver wishes. He requires a 

 long pause in the motion of the lathe when the 

 shuttle is traversing the shed, and a very short one 

 on striking the shot home, and therefore the hand 

 loom weaver, to gain speed, moves the lathe quickly 

 from the fell, that the shuttle may be admitted 

 into the shed as soon as possible, and then slowly 

 retards the motion of the lay. Mr Buchanan 

 accomplishes this motion by his means ; but there 

 is always a perceptible harshness of action in the 

 motion of the lathe by the eccentric wheels; which 

 is increased when the form of the wheels is not 

 good and the speed high. Now this very motion, 

 without any drawback, is accomplished by the 

 crank itself, merely by placing the crank shaft 

 lower in the loom than that part of the lathe 

 to which the connecting rod is attached for the 

 communication of motion from the crank. This 

 adaptation therefore, of the cratik, renders Mr 

 Buchanan's eccentric motion entirely useless. 



The motion of the cloth beam is likewise various, 

 but it is usually accomplished by the sword of the 

 lathe. The lever which communicates motion to 

 the cloth beam, is so placed as to lie within the 

 traverse of the lathe; which as it vibrates, pushes 

 it out of its way, and thus gives motion to 

 the beam. This method of taking the motion is 

 objectionable in so far as it has a tendency to disturb 

 the action of the lathe; it may, however, be easily 

 remedied, as is frequently done, by taking the 

 motion from one of the two shafts. 



Weaving, of cotton especially, consists of two 

 processes; weaving, properly so called, that is, the 

 motions for interlacing the warp and the weft ; 

 and the preparation, or dressing of the yarn for 

 being woven. The rapid rotation of the spindle 

 on its axes in twisting the thread, throws out by 

 the centrifugal force of the motion the ends of 

 the fibres on its whole surface. The threads are 

 therefore very rough, and if brought in this state 

 to be woven, they would entangle each other in 

 the shedding, and the whole web in a short time 

 would be a mass of breakage. The object of 

 dressing is to lay these fibres along the surface of 

 the thread, and thereby strengthen it to stand 

 the process of weaving. This process was done 

 by hand in the power loom, by the weaver 

 who had the charge of it while the loom was 

 going on. The yarn, therefore, was sustaining 

 the action of two processes at once, and the 

 breakage thereby was not only greatly increased, 

 but the work likewise must have been imper- 

 fectly done. The only gain in weaving by 

 power is by enabling one person to manage more 

 than one loom ; when one individual was indis- 

 pensible to each loom, it would have been better 

 to have allowed the weaver to dispense with 

 the machinery altogether, and weave by the com- 

 mon method ; and indeed, this is the result that 

 must have taken place, but for the invention 

 of the dressing machine. This great invention, 

 which rendered the power loom successful. 



