CLOTH MANUFACTURE. 



683 



Cloth namely, that durability and thickness is the first object 

 Manuiac- i n coarse goods, and beauty and transparency in fine. It 

 k *""' . would afford but a slender recommendation to a birth-day 

 ~**V dress, to possess that warmth and durability which would 

 form the chief excellence of a watch-coat, or blanket ; 

 and it would be equally useless, to gire to the coarse ma- 

 nufacture, which is valuable in proportion to the shelter 

 which it affords from the inclemency of wind and wea- 

 ther, qualities which could only afford gratification to 

 the eye, by the sacrifice of every comfort. 



The warp of a web being longitudinally stretched in 

 parallel straight lines, and the woof or waft being inserted 

 at right angles to it, the substance produced as cloth, will 

 bear a strong analogy to the form of a raft of wood, con- 

 sisting of two platforms of square beams, laid across each 

 other and fastened together ; or if we suppose that a num- 

 ber of cylindrical pieces of wood, such as the topmasts or 

 yards of a ship, are laid parallel to each other, and that 

 cords or ropes are interwoven between them to keep 

 them together, we shall have a very exact representation 

 of a piece of cloth, on a scale of such magnitude as will 

 admit of all the proof of actual measurement. In cloth, 

 even of the finest kinds, the length, breadth, and number 

 of the component threads or cylinders, in the piece, may- 

 be ascertained with equal precision ; but, from the small- 

 ness of the diameter of every thread, it becomes impos- 

 sible to measure them actually, with any degree of ac- 

 curacy. The length and the weight or mass, however, 

 being known, the diameter may be found by a calcula- 

 tion, which bears evident marks of great exactness, and 

 we may then safely assume that no difference can arise, pro- 

 vided the densities of all threads are the same. Upon this 

 point, however, there has been some difference of opinion, 

 and the subject has been. so little investigated in a scien 

 tific manner, that it would be perhaps presumptuous to 

 draw any absolute conclusion upon the subject. We shall 

 therefore only observe, that the argument upon which the 

 increase of density in fine yarn above coarse chiefly rests, 

 is this, that in spinning fine yarn, a greater number of 

 revolutions of the wheel are necessary to give the twist 

 sufficiently to produce a sufficient cohesion of the fibres, 

 than in coarse. This is incontrovertibly true ; and as the 

 filaments or fibres, by this twisting, assume the form of a 

 crew or spiral, the point to be decided is, simply whe- 

 ther, by thi-i excess of twisting, the fibres of fine yarn 

 tre not brought more cloely into contact than those of 

 coarse; and consequently that the diameter of the thread 

 ii diminished in the same proportion that the twisting is 

 increased. It must be obvious, that where the circum- 

 ference exposes a small surface, many more revolutions 

 will be required than where it presents a large one, be- 

 fore all the fibres can be sufficiently stretched ; and, 

 consequently, that fine yarn will always require more 

 twisting than coarse to give it the same tenacity. But 

 as every thread from the stoutest cable to the finest 

 which human art and industry can produce, contracts 

 in length, by the operation of twisting, there seems rea- 

 son enough to conclude, that the compressing power 

 exerted, acts either entirely upon the length, or that 

 what is exerted on the diameter, must bear a very small 

 proportion indeed to the other. We may therefore in- 

 fer, that the nearest approximation to actual truth, will 

 be to consider a rope or thread like any other solid cy- 

 linder, and that the difference of density will not very 

 materially affect the calculation. Upon this principle 

 we shall easily arrive at a very considerable degree of 

 mathematical precision, and upon the whole eome nearer 

 to actual truth, than by any other hypothesis yet 

 known. 



In Plate CXCIII. will be found some figures, expla- 

 natory of what further remarks may be necessary on this 

 subject as connected with fabric ; and it will also be 

 useful in conveying correct ideas of the varieties of tex- 

 ture most generally used, both in the substantial and 

 flimsy descriptions of woven goods. 



Figure 1st of Plate CXCIl 1. may be supposed to re- 

 present any solid body composed of various parts, lashed 

 together. If the darkened squares are so many parallel 

 beams of wood, connected by cordage, we arrive at once 

 at a precise idea of texture. The length of these beams 

 is known by measurement ; the breadth of the whole 

 consists of the aggregate number of pieces of wood, 

 added to the space which the cords occupy between 

 each, and which will be more or less, in proportion to 

 the thickness or diameter of these cords. It is also ob- 

 vious, that it is impossible to bring the beams into ac- 

 tual contact ; for were we to suppose that the connect- 

 ing or lashing cords were actually as fine as human hairs, 

 they must still occupy some portion of space. The 

 thickness, it is equally apparent, is that of one beam and 

 one cord ; but if we suppose the cords everywhere in 

 actual contact, we may then also suppose that the thick- 

 ness is that of the beam and two cords. Now, it is 

 hardly possible to conceive, that in a flexible substance, 

 such as those used in the fabrication of cloth, any means 

 could be devised, to bring every thread of woof into ac- 

 tual contact, so as to cover the warp both above and be- 

 low. We may therefore very safely assume, as a general 

 principle, that the geometrical thickness of cloth, is the 

 measure of the diameter of one thread of the warp, added 

 to the measure of the diameter of one thread of the woof; 

 and that when those measures are equal, the thickness of 

 the cloth is, of course, double the diameter of one of the 

 threads of which it is composed. Thus we have the utmost 

 thickness of fabric of which cloth is capable, and more 

 than even the strongest canvass, with which we are ac- 

 quainted, can possess. Indeed a fabric of this kind, 

 were it even easily attainable, would be practically use- 

 less ; for the immense increase of density, would so com- 

 pletely takeaway every degree of pliancy and flexibility, 

 that the fabric would be as unsuitable for any purpose 

 to which cloth is properly applicable, as a fir plank, or a 

 sheet of copper. 



In Plate CXCIII. Fig. 2. is a representation of a sec- 



r 1 t r r i i i i i 



tion or cloth of an open fabric, where the round dots which 

 represent the warp, are placed at a considerable distance 

 from each other. In this figure we see very evidently, 

 that the geometrical thickness of cloth may be consider- 

 ed in the duplicate ratio of the diameter of one thread ; 

 for if we suppose the two parallel lines which bound the 

 figure, to represent two boards used in the calender press 

 wnere the cloth is finished, and that they are to be 

 pressed together by any mechanical power, we shall at 

 once see that their effect must immediately flatten the 

 threads, and divest them of their cylindrical form. 



Fig. 3. of Plate CXCIII. may be supposed a plain 

 fabric of that description, which approaches the most 

 nearly to any idea we can form of the most dense or 

 close contact of which yarn can be made susceptible. 

 Here the warp is supposed to be so tightly stretched in 

 the loom, as to retain entirely the parallel state without 

 any curve or flexure whatever, and the whole is therefore 

 necessarily given to the woof. This mode of weaving 

 can never really exist ; but if the warp be sufficiently 

 strong to bear any tight stretching, and the woof be spun 

 very soft and flexible, something very near it may be 

 produced. This way of making cloth is well futed for 

 those goods which require to give considerable warmth, 



CXCIII. 

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CXCIII. 



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p r . A Tit 

 CXCIII. 

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