The shuttles themselves are very ingeniously constructed so as to accommodate the greatest possible amount of filling, together with the necessary space for springs to properly manipulate the tensions. Each shuttle is bored through at either side so as to allow for the insertion of a fine recoil spring, which is made fast at one end of the drilled hole at the back of the shuttle. To the other end of the spring is attached a small porcelain eye, through which is threaded the weft, making it possible to govern and take up by the action of the spring the loose filling which is thrown off as the shuttle passes and repasses through the shed. These side recoil springs are not only useful for the taking up of the loose filling but allow for a variety of threading up methods, so as to assist in the governing of the tension of the weft at one or both sides of the web, and thus afford a means of weaving the goods level. They aid in correcting any tendency to long and short sided goods, of which we will say more later. At the back of the quill or shuttle spool is arranged another spring on which is swivelled a porcelain device which presses against the quill, and can be so regulated as to govern the tension. This spring is so tempered that the most delicate adjustment of tension can be made. RACK AND PINION MOVEMENT The shuttles across the entire width of the loom are drawn to and fro by what is known as the rack and pinion movement. (See Fig. 2). This method has pretty generally superseded the old-time plan of rise and fall pegs. The rack runs back and forth in a slot grooved in the top of the lay bed, A, the entire length of the loom. To the rack is attached leather straps G, or heavily woven fabric straps, with which the rack B is pulled to and fro at each pick of the loom. The rack is of wood, having rounded teeth-paced approximately one-third of an inch apart. Into the rack are meshed pinions C, two to carry each shuttle E, the teeth of which are correspondingly spaced. The rack is set into a wood carrier which is about one inch deep and one inch wide, and the full length of the lay. The pinions are made of either raw hide or paper fibre, and these pinions again mesh into a series of racks D, grooved in on the under side of each shuttle, and thus drive the shuttle to and fro across the web spaces J. The constant travel of the driving rack running in the groove at the top of the lay bed necessarily produces more or less wear at the bottom of the rack. It therefore is advisable to place underneath this rack a false bottom of wood of about ¼-inch thick, which after becoming worn by constant use and contact with the ever-moving rack may be easily taken out and replaced by a new one, thus keeping the rack and pinions and shuttles at all times in proper mesh with each other.