The other movement is known as the end-cam method, where a small shaft is set at the end of the loom, running at right angles to the driving shaft (See Fig. 4) from which it is driven by bevel gears. On this short shaft are set the cams, usually 8 or 12 in number, which have a series of grooves at their center so as to afford means of timing them in different positions on a feather key which runs the full length of the shaft. These cams operate what is known as the cam jacks, which may also be seen in Fig. 4. The jacks are hung at the middle and are moved backwards and forwards by the cams, communicating movement to the various harnesses. The harnesses are connected at both the top and bottom of the jacks. This connection at both ends of the jacks makes it possible to run the looms at a very high rate of speed, as there are no weights or springs to contend with, which limits speed. While the first described method of direct cams has some advantages over the end cams, such looms are not nearly so economical to operate as the end cams on account of the limited speed attainable. While the harnesses are lifted by means of the cams they have to be pulled down by weights or springs. The means of shed adjustment, however, enables the attaining of a well graded shed. Furthermore, the cams themselves can be so set on the shaft as to afford means of timing the movements of the different harnesses so that excellent and easy shedding results may be obtained. But the one great disadvantage is the limitation of the weaves attainable, which limitation is largely overcome by the end-cam method. When the direct cam movement is used, and where the goods being woven are of such a character as to demand a very slow speed of the loom, it is practicable to bring the harnesses down by weighting them with wide flat weights of the requisite size. But where higher speed is required than is advisable for weighted harnesses, springs are more desirable. The simplest form of pulling do the harnesses is by the use of floor blocks and direct springs. There is, however, a disadvantage in using the direct spring on account of the pull increasing until the extreme lift of the harness is reached, which necessarily increases materially the power expended in operating same and makes an unnecessary strain. The better way is to use what is known as spring jacks, which have an easier pull than the direct spring inasmuch as the load eases off on the pull, diminishing from the greatest pull at the start to the lightest pull at the extreme lift on the lever, so that the load is uniformly distributed all through the movement and less power is employed. CHAPTER II. _Looms Should Be Adapted to Make a Wide Variety of Goods—Take-Up and Let-Off Motions—Making the Rubber Warps for Different Classes of Web—Importance of Uniform Tension—Defects from Uneven Tension and Chafing of Threads_