The main cylinder c ie placed in reverse order as compared with the small one d, being so arranged that the greatest portion of its surface may be utilized for drying, the same end also being secured from the small one d. The construction of these cylinders should be such as to with stand all danger of explosion from the pressure of the steam, which is 4-15 lb. an in. Provision is made to secure a complete discharge of the water resulting from the condensation of the steam by which they are heated. If this be neglected, their efficiency for drying purposes is greatly im paired. The cylinder-shafts, or centres, revolve upon loose-pulleys, which is a great improvement upon the old plan of stuffing-boxes, and diminishes the strain upon the yarn. The condition of the cylinders should be frequently examined, the best means being to turn them with the hand when the yarn is slack : if they revolve easily, and seem to be properly balanced, the test may be regarded as satisfactory. The periphery of the cylinder is usually composed of strong tin plates ; and the ends, of steel ; the interior is well stayed. In some cases, however, the tin soon wears off, and exposes the iron surface to the corrosive action of the acids of the size, which soon results in iron stains upon the warp. To obviate this risk, copper cylinders are sometimes used, and, though more costly in the first instance, they make better work, and will be found more economical in the end. An equilibrium-valve, and deadweight safety-valves for each cylinder, should be attached to every machine. The cylinders should contain manholes at one end, so that interior repairs can be effected without taking them out of the frame. A steam-trap should also be attached to each, for carrying of the condensed water. In the event of only one being used, the pressure of the steam, which is usually greater in the large cylinder, interferes with the delivery of water from the small one.
Steam is admitted into the cylinders c and d through the chests e e' ; *these are provided with safety-valves, set to allow the steam to escape within a pressure to which the cylinders can safely be subjected. The fan f completes the drying, and cools the yarn as it passes from the cylinders, over the carrier-rollers g gt, to the series of rods h, whose function is to separate the threads of the warp from each other after they have passed through the size, which has a tendency to make them adhere. An expanding wraiths or reed extends across the frame between t and the marker j, by means of which the sheet of yarn is evenly spread over the space between the flanges of the beam 1. The marker j is a small bowl, which dips into a trough containing colouring matter, and marks the warp in prescribed lengths for the guidance of the weaver. The figured plate k, with the pointer seen in the plan, is the register, showing the length of warp which has passed upon the beam 1 at any moment. The machine is stopped by the levers n a, of which there are several, conveniently placed for the sizer, at different parts of the machine.
Until 1874, the beam I was, and, in many existing machines, is now, driven by a pair of cone drums, by which the steam can be accommodated to the increasing diameter of the beam 1, caused by the winding on of the warp. This necessitated constant vigilance on the part of the sizer,
whilst the result of the beet attention was unsatisfactory, owing to the variation of speed causing the yarn to be immersed in the size for longer or shorter intervals as the speed was slow or quick. In the year named, Howard and Bullough introduced the triple roller arrangement, which has done for the sizing-machine what the positive taking up motion has for the loom. This improvement has been widely adopted, and found to obviate most of the practical difficulties previously experienced.
The triple roller arrangement greatly simplifies the machine, dispensing with cone-drums, strap-fork, worm, and guide-shaft, existing in the old frame ; and yields, without the attention of the sizer, that which could not be obtained before, namely a perfectly uniform speed in winding the warp upon the beam. Uniform sizing and drying is the consequence—a great improvement upon the preceding condition. The lettere D E F will show the arrangement of the rollers. The bottom or draw-roller E is driven at a positive uniform speed from the first driver, and, as it drives the delivery-rollers I in the size-box by means of the side-shaft p, it determines the speed at which the yarn passes through the machine. The proper speed, having been decided upon, remains unaltered until circumstances require it to be changed, which can be accomplished in a moment by putting a larger or smaller pinion on the boss G geared into the carrier-wheel El, and so increasing or diminishing the speed of the drawer-roller E. Stopping a sizing-machine in the midst of work is objectionable, from the fact that a great strain is often put upon the yarn to over come the inertia of the beams, rollers, and cylinders, whilst, during the stoppage, the squeezing roller—should it be of metal—and the yarn are baking together, and damaging the warp ; if the roller be of wood, it gets so often out of repair, and, by rapid wear, varies so unequally in its diameter, that it is undesirable to apply positive driving to it, on account of its liability to deliver more or loss yarn than required by the copper roller in front of it ; hence results the great evil of the sizing-rollers having to be turned by the drag of the wet yarn, which is strained and broken, and its elasticity almost destroyed. The slow-motion apparatus of the inventors dispenses with the necessity of having the sizing-roller of wood, to avoid baked places upon the yarn, because, with the reduced speed, broken threads, called " lappers," can be out off, and doffing, and all necessary operations, can be performed without stopping, and therefore without risk of the size baking. The roller may then be of metal, and be turned to the exact diameter required, which, to allow of the yarn being in the best condition for absorbing size, requires that it should be a little larger than the finisher-roller I in front of it. With this arrangement, it can be driven positively from the side shaft, in which ease the quality of the yarn undergoes no deterioration from excessive strain.