984 TEXTILE FABRICS 



slackly twisted cotton or woollen yarn, where the fibrils of the stuff, being but slightly 

 brought into contact, are rough and oozy, a great appearance of thickness and 

 strength may be given to the eye, when the cloth is absolutely so flimsy that it may 

 be torn asunder as easily as a sheet of writing-paper. Many frauds of this kind are 

 practised. 



In fig- 1962 is given a representation of the position of a fabric of cloth in section, 

 as it is in the loom before the warp has been closed upon the woof, which still appears 

 as a straight line. This figure may usefully illustrate the direction and ratio of con- 

 traction which must unavoidably take place in every kind of cloth, according to the 

 density of the texture, the dimensions of the threads, and the description of the cloth. 

 Let A, B, represent one thread of woof completely stretched by the velocity of the 

 shuttle in passing between the threads of warp which are represented by the round 

 dots, 1, 2, &c., and those distinguished by 8, 9, &c. When these threads are closed 

 by the operation of the needles to form the inner texture, the first tendency will bo to 

 move in the direction 1 b, 2 b, &c., for those above, and in that of 8 , 9 a, &c., for 

 those below; but the contraction for A, B, by its deviation from a straight to a curved 

 line, in consequence of the compression of the warp-threads 1 b, 2 b, &c., and 1 a, 2 a, 



&c., in closing, will produce by the 

 action of the two powers at right 

 angles to each other, the oblique or 

 diagonal direction denoted by the 

 lines 1, 82, 9, to the left, for the 

 threads above, and that expressed 

 by the lines 2, 83, 9, &c., to the 



1963 right, for the threads below. Now, 



as the whole deviation is produced 

 by the flexure of the thread A, B, if 

 A is supposed to be placed at the 

 middle of the cloth, equidistant from 

 the two extremities, or selvages as 



^.Af _ J L'*e^^!!Sp* a '' g '*'C'* T^Tf* ** f 1 **^ they are called by weavers, the 



thread at 1 may be supposed to 



move really in the direction 1 b, and all the others to approach to it in the directions 

 represented, whilst those to the right would approach in the same ratio, but the line 

 of approximation would be inverted. Fig. 1963 represents the common fabric used 

 for lawns, muslins, and the middle kind of goods, the excellence of which neither 

 consists in the greatest strength, nor in the greatest transparency. It is entirely 

 a medium between/^. 1960 and fig. 1961. 



In the efforts to give great strength and thickness to cloth, it will be obvious that 

 the common mode of weaving, by constant intersection of warp or woof, although it 

 may bo perhaps the best which can be devised for the former, presents invincible 

 obstructions to the latter beyond a certain limit. To remedy this, two modes of 

 weaving are in common use, which, while they add to the power of compressing a 

 great company of materials in a small compass, possess the additional advantage of 

 affording much facility for adding ornament to the superficies of the fabric. The 

 first of these is double cloth, or two webs woven together, and joined by the operation. 

 This is chiefly used for carpets ; and its geometrical principles are entirely the same 

 as those of plain cloth, supposing the webs to be sowed together. A section of the 

 cloth will be found in fig. 1964. See CAEPETS. 



Of the simplest kind of tweeled fabric, a section is given in fig. 1965. 

 The great and prominent advantage of the tweeled fabric in point of texture arises 

 from the facility with which a very great quantity of materials may be put closely 



together. In the figure, the warp is represented by the dots in the same straight 

 line as in the plain fabrics ; but if we consider the direction and ratio of contraction, 

 upon principles similar to those laid dowu in the explanation given of fig. 1962, we 

 shall readily discover the very different way in which the tweeled fabric is affected. 



When the dotted lines are drawn at a, b, c, d, their direction of contraction, instead 

 of being upon every second or alternate thread, is only upon every fifth thread, and the 

 natural tendency would consequently be, to bring the whole into the form represented by 

 the lines and dotted circles at a, b, c, d. In point, then, of thickness, from the upper 

 to the under superficies, it is evident that the whole fabric has increased in the ratio 



