For the draught of the warp, or its order of insertion in the heddles, it is, in the first instance, necessary to ascertain whether the two sides of the pattern are simi lar, or dissimilar ; for in the former case only one half of the heddlcs will be requisite, which are indispcnsi We in the latter. By similarity of the sides, the follow ing meaning is to be understood. Let an ornament or flower consist of any given number of threads, as 20,40, 60, 80, or 100; then if, in the first instance, the 10 threads to the left form an appearance exactly similar to the 10 threads to the right, but inverted upon the cloth, the pattern is similar, and may be wrought with 10 leaves ; if not, it is dissimilar, and will require 20, ex clusive of what may be requisite for plain cloth in either instance. The pattern in the figure is dissimilar, and therefore requires twice the number of leaves which would be necessary in one diverging equally from the centre. In this pattern, 25 leaves are used, indepen dently of that in the front, through which every alter nate thread is drawn, in order to form the ground of the fabric. Hence, if plain cloth be required, as it is in the intervals between the flowers, the aggregate of the 25 leaves, including one half of the warp, while the front leaf singly contains the other half : these two, wrought alternately, will produce the plain, whilst the others may be so varied in succession as to form any flower whatever, whose range does not exceed the number of threads contained in those leaves. The draught of the warp is uniform and successive from left to right, and hence the whole fabric may be covered with flowers if required ; or the weaver may, at his discretion, fill only every second, third, or fourth, with the ornamental woof, and thus produce a pattern richer or slighter, as may be found convenient.
The number of treddles necessary are 22. Of these, the two represented at the right hand, and distinguished by the letters A, B, are intended for the plain part of the fabrick ; for A, when depressed, will raise the front leaf, containing one half of the warp, and B will exactly re verse the effect, sinking the front leaf and raising all the others. The remaining treddles, when used, will raise in varied succession the ornamental part, and produce the pattern intended. The cross lines drawn in the figure are very similar to those in the design paper, which is the general rule by which weavers are directed in their operations ; and a copious account of which, illustrated by references to the most extensive species of ornamental workmanship, will be found in the article CLOTH MANUFACTURE. Let whatever part of the pat tern, where the warp is to be raised above the woof, be represented by the marks and dots upon the intersec tions of the peddles and treddles, and an exact rule will be given to the weaver for the application of his raising cordage. In a part of these the whole intersection is filled, which assimilates the appearance to that upon de sign paper ; in the remainder, dots only are used, which is the way generally adopted in actual practice. These
marks, therefore, denote raising cords, and where no mark is applied, sinking cords are to be used ; so that the whole warp may be effected either in one or the other way, by the pressure of every individual treddle. Upon this general rule depends the formation of every flower which can be woven upon cloth, whether incor porated into the fabric, as in damask, or effected by se parate woof, as in brocading.
The cording marks, in plans of this description, may in general be reduced to three different descriptions : 1st, Those in which every part of the figure is inde pendent and dissimilar.
2d, Those in which the two sides are similar, but where the top and bottom differ.
3d, Those in which every part diverging from the centre, is similar to that opposite to it.
Of the first of these, the figure to which reference has been already made, is an example ; and this, whe ther woven as a brocade, or as a spot, is the most com prehensive kind.
In Plate CIV. Fig. 3, will be found an illustration of the second ; and this we shall suppose is to be woven like what is termed a common spot.
Spotting, in point of show and effect, is considerably inferior to brocading ; but its great difference in labour, and consequently in price, gives it many advantages over the former, which is much too expensive for extensive and general use. Spotting is formed by the insertion of woof much coarser than what forms the general fabric, and passes clear of every part of the texture, the figures only excepted. The intervals of the coarse woof are clipped away with scissars after the cloth is taken from the loom, and before it is sent to be bleached and finish ed. From this circumstance, all spots are liable to a defect in appearance, from which brocades are totally exempted. If this spot be supposed to represent a club, only one half of the figure is necssary for the plan of the cording ; for in the way in which the drawing of the warp is done, two threads upon opposite sides of the Fi gure being inserted in the same leaf, the sides will be similarly formed by half of the mounting used in dissi milar or independent spots. The mounting here con sists of two separate and independent figures, which are to be wrought alternately ; and any portion of the warp being inserted in the plain leaves A and B, the figures may be either contiguous, or removed to any distance which may be thought proper. A spot where all the figures are contiguous, without any intervention of plain cloth, is called an allover ; those where the plain spaces are equal to those allotted for the spotting are denomi nated half covers, and so of others. This spot is con tained in 32 leaves, of which A and B are reserved for the plain intervals, and the remaining 30 for the two spots, 15 being allotted for each.