BOUK, BuxE, or BOOR IUSLINS, known also by the name of Wire Muslin, from the transparency of the fabric. is the lightest and most flimsy species of all the varieties of Indian manufacture. The British imitation originated in Sebtland about the year 1785, since which time it has been prosecuted to great ex tent. In England it has been attempted without much success, for the excessive lightness of the fa bric, and consequently the great care which is requi red to preserve the warp from breaking, requires great delicacy, both of pressure in opening the warp, and nicety of hand in striking it equally borne in the cloth. The lightness of the fabric hi ing so great, it be comes impossible, even for the nicest and most expe rienced. weaver, to regulate the motion, or oscillation of his lay, so as to bear sufficiently light, were the reed firmly fixed between the shells, as in stouter fa brics. To remedy this, it becomes necessary that the reed should be fitted so as to yield easily to a very slight pressure, and return to its position as soon as that pressure ceases to act upon it. For this pur pose, in weaNing all the light fabrics of muslins, the reed is placed so as to yield easily. In the jacconett fabrics. an instrument, known by the name of a pair of flyers, is used. This is exactly an inverted lay of a very light construction. It consists of two perpen dicular arms or swords, like the common lay, but constructed very light and thin, so as to bend easily like a spring. The horizontal part forms the upper shell for the reed ; and thus the groove for receiving it is inverted, being placed above instead of being be low. The upper extremities cf the arms are tacked to the back of the swords of the lay by two nails ; and these arms, being very thin, easily yield, whenever the reed comes in contact with the body of the cloth. The quantum of spring is very easily regulated, by tying two small pieces of twine round the swords, both of the flyers and lay. When these cords are placed high, a considerable part of the spring being below, will yield very easily ; and as they are shifted downwards, nearer to the reed, the springing part becoming shorter, the reed always opposes a greater resistance before it yields. The cords thus answer every purpose of a moveable fulcrum, and, by shift ing them, the power of the spring may be increased or diminished in an instant.
For the very light fabrics, such as those which form the subject of this article, a double set of these flyers has been invented. This contrivance is similar to the former : it consists in having a second pair of flyers, with the groove inverted, to receive the under as well as the upper part of the reed, so that it yields below as well as above. Flyers of this construction are not, however, in much estimation ; and it may be observed, that, in all mechanical professions, the ope rative tradesmen, although seldom able to account for their opinions, are almost universally directed, by simple experience, to the choice of the best. In the
first place, the double flyers, as they are called, al though they yield both above and below, yield equally, or nearly so ; consequently, the divisions of the reed always remain perpendicular to the horizon, and the action of the reed upon the cloth is uniform ly at right angles to the warp, or nearly so. Thus, the impetus being direct, the force is applied in that way in which it will produce the most powerful ef fect ; but the very object of this contrivance is not the acquisition, but the diminution, of effective power ; consequently, the more obliquely the force is applied, the better for the purpose. In the second place, the double flyers are not only expensive in their con struction, but, from their complexity, very liable to be put frequently out of order ; for unless the whole four cords, which regulate the spring, are kept, not only at an exact uniformity of tension, but also at an exactly equal distance from the point of percussion, where the reed acts upon the cloth, their resistance will be unequal, and the whole fabric liable to be clouded. Experience proves, that an operative wea ver, totally unacquainted with the laws of motion and theoretical principles of mechanics, will very sel dom be able to preserve that uniformity necessary for the regulation of this machine, and even if he were, the very change of tension, produced by vicissitudes of weather, would be a source of very vexatious trou ble and delay. The double flyers have, for these reasons, been almost universally abandoned, and a very cheap, simple, and efficacious substitute adopt ed. This consists merely of a stout woollen cord tightly stretched between the swords of the lay, and to which the upper rib of the reed is tied, at inter vals, with pieces of packthread, or fine twine. Wool len is preferred to any other substance, because it is less liable to constriction, or relaxation, from changes of weather, than any other fibrous substance with which we are acquainted. The upper shell, or cover of the reed, is generally removed, on account of its weight, and a slight spar of wood nailed between the swords in its place, with which the weaver gives the necessary vibration to the lay. Front the lightness of the fabric, great care is necessary in picking and dres sing the yarn, and great uniformity in working the treddles and lay ; and, upon the whole, the weaving of bouk muslins requires patient and unremitting at tention, in a much Superior degree to active exer tion.