According to the strength and elasticity of the sample, a curve of a certain shape will be traced on the paper, a very elastic sample will give a flat line or curve, whilst a less elastic sample will give a more vertical line or curve.

In LEUNER'S MACHINE the recording sheet is mounted on a drum, over this drum there is a pencil placed vertically in a laterally moving frame attached to the traversing screw. Α rotary motion can be given to the drum by means of bevel gears worked from the moving jaw. Thus, if an inelastic sample is being tested, a straight line parallel to the axis of the drum will be drawn, but if the jaw is moved without the spring being stretched then the drum will revolve and a concentric line will be drawn, therefore, assuming that an ordinary sample of cloth is being tested, a curve will be drawn representing the combination of the breaking load and the extension to breaking.

Provision is made for testing the accuracy of the springs with dead weights.

The machines are only suitable for narrow strips of cloth as the maximum load is about 20 kilos.

OLLIVIER'S MACHINE is of the vertical dead weight type, of which there are many examples. This dynamometer is illustrated at Figure 10 and consists of a vertical screw which is attached to the lower jaw, the upper jaw is carried by a strong band passing over the pivot shaft on which is mounted the weighted lever; pawls and a notched quadrant serve to hold the weighted lever so that the point of breaking may be observed.

Provision is made for attaching dead weights to hooks on the upper jaw, so that the efficiency of the machine may periodically be tested for accuracy.

A sample of the desired width is first placed carefully in the upper jaw and made secure, it is then attached with equal care to the lower jaw. Rotation is now given to a nut mounted on the vertical screw, which causes the screw to descend, and, as tension is thus put on the cloth, the weighted lever is raised until the sample is broken, when the breaking load may be read on the side of the quadrant. The elongation to breaking is shown on a graduated brass plate suitably fixed.

PERSOZ'S PERFORATING APPARATUS, Figure 11. An interesting addition has been made to this dynamometer by J. PERSoz, of the Silk Conditioning House of Paris, the object of

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FIGURE 11. - PERSOZ PERFORATING APPARATUS.

which is to test the strength of the cloth by perforation, and it will be readily seen that by this plan both warp and weft threads are put under tension and broken, so that in this particular it differs from all other machines.

The method consists of holding the sample between two circular metal discs, and presenting the cloth after the manner of a drum top to the perforating medium. This latter takes the form of a rod on the end of which is mounted a metallic sphere after the style of a cup and ball. The cloth is fixed in a frame to which a downward movement is given by means of the vertical screw, the metallic sphere is mounted in a frame which is attached by hooks to the pivot shaft, and, as the force of the

screw presses the cloth upon the sphere, the weighted arm is raised until a rupture takes place, the power expended on rupturing the cloth being indicated on the quadrant. The deflection of the cloth up to the point of rupture is also recorded. A planoscope is provided, so that the exact start of deflection may be noted and from this point duly measured. In the large drawing, Figure 10, the perforating mechanism is shown in position and at the side the cloth breaking attachment is shown.

SCHOPPER'S CLOTH TESTING MACHINE, Figure 12, is a fine example of the vertical type. It is made in many forms and in many strengths. It may be worked either manually, mechanically, electrically, or by water under pressure. In the machine illustrated the centres of the weight lever are in ball bearings, provision is made to read the stretch to breaking in millimetres and in percentages. The material to be tested may be up to 50 millimetres wide and may be from 100 millimetres to 400 millimetres long, there is a special device for ensuring that the some length is tested each time. The machines are built for tests varying from 100 kilos. to 1,500 kilos.

It will be noticed in this machine that the width is rather narrow, being less than 2 inches, but the tendency is in that direction, it being considered better to test three 2-inch strips than one 6-inch. The irregularities are more easily found by this plan, and it is easier to fix a narrow strip in position without getting it twisted. Machines with wider jaws can, however, be obtained from this firm. Provision is made for recording the elongation and also any error there may be in the particular machine.

COMPARISON OF CLOTH TEST WITH SINGLE THREAD TEST.

It is proposed to institute a comparison between the strength of the single threads and the strength of the woven cloth made from the threads, so that a manufacturer may know what strength of yarn to use in order to obtain a certain result.

It is usual to test the strength of a sample 6 inches wide, but it