Double-lift Jacquards are not yet used beyond the experimental form, as the shaking cannot be done as easily as in a dobby with shafts, but we have heard of the thing being done by knotting the harness above the comber board and lifting the board a little when the cross is being made. Messrs. Eccles, of Preston, some years ago obtained a patent for lifting the standard ends by means of a third knife or griffe. The additional knife was given half the lift of the other two, and its function was to lift the standard ends half way when the doup ends were crossing to the other side. This would, no doubt, enable the cross to be made with ease in a double-lift Jacquard, but the principle is not likely to be a great success.
The doups in leno Jacquards are very liable to wear out unless made of very good material, and some experience is necessary before the harnesses are worked satisfactorily.
An imitation of the fabric usually woven on this harness is sometimes made by making one end cross three ends in the leno, and weave plain in the figure. This can be done with an ordinary harness with a doup heald in front lifted every other pick, on the same principle as in Fig. 144.
Terry looms are extensively used in the cotton trade, chiefly for weaving towels, but often for striped dress and similar fabrics where terry or loop pile is combined with other weaves. The loops can be formed either on one side or both sides of the fabric, but the loop formed in these looms is not to be compared with real loop pile woven over wires, as the loops cannot be formed with the same regularity. There are numerous terry motions, as they are called, most loom makers having their own speciality. Fig. 150 is the design for a good terry cloth. It will be noticed that the second and fourth ends are the reverse of each other: one is up for four picks and down for one, and the other is down for four picks and up for one, whilst the other two ends are nearly plain. The first and third ends form the ground, and the second and fourth ends the pile or loops. There are five picks to the round.
The ground warp is on a separate beam to the pile warp, the latter having a special tension to let off the required quantity to form the pile. At the second pick in the pattern, just where the pile warp is bound, the reed is made to beat further up than on the two preceding picks, thus forming a pile by sending one half the pile ends to the face and the other half to the back. The reed beats up to the front for the second, third, and fourth picks in the pattern, as given at Fig. 150, following which the reed is held back for two picks. Fig. 151 is a good motion for making the reed occupy the two positions when beating up. P represents the slay, and a lever, A, centred at D, is so constructed that when A is pulled down the reed is pushed forward. The rod R is connected to a lever, M, on a shaft, N, placed under the loom. A rocking motion is given to this shaft by a box cam, P, five to the round (Fig. 152), so shaped as to lift and depress the lever QS for the required number of picks. This cam is driven from the picking shaft. By pulling the rod R downwards the reed is moved forwards, and the rod will have to be kept down for three picks and moved up for two picks, so as to keep the reed in its front position for three picks and a little way back for two. The effect required is really to lengthen the crank-arm at will, and the principle of the knuckle joint may be used in its simplest form--that is, by having the crank-arm jointed in the middle and fixed a little out of a straight line, and by straightening the arm when the front position of the slay is required.