of the structure, E C H, about its center of rotation was made equal to the moment of A C D about the center. The wires, B and F, are attached at their ends to supports which are both rigidly connected to the same base or foundation. If this base, the normal position of which is horizontal, is tipped slightly, the weights, C and H, will both tend to fall in the same direction. But suppose the right hand end of the base is raised, causing both of the weights to tip to the left of the vertical, D, tending to fall over, the left tends to raise the right hand end of the beam, and the connecting piece, J H, also tending to fall to the left, tends to lower the left hand end of E and the piece, J. The moments of the structure, E C H, and A B D being equal, and one tending to raise J and the other to lower it, the effect will be zero, and J will remain in its normal position.

It is not at all necessary, however, to have the weights and dimensions of the structure, E C H, equal to those of A B D. All that is necessary is that the components of the weight of each part of the structure which act vertically on J shall be equal and opposite. For, if the left end of the beam, E, is made shorter than the right end of the beam, A, a given angle of rotation of the beam, A, will cause a greater-angle of rotation of E, consequently will tip the weight, H, further from the vertical than the weight, D, is tipped, and in that case the weight, D, must be made smaller than H, to produce an equal and opposite effect upon J. In practice it is convenient to make the beam, E, only one-fifth to one-twentieth as long as A, and to correspondingly reduce the weight, H, relatively to D. In this case, on account of the angle of rotation of the beam, E, being greater than the angle of rotation of A, the beam, E, becomes a multiplier of the indications of the primary beam, A.

Mr. Kent has devised a modification of Dr. Springer's system, which is shown in Fig. 3. It is applied in those varieties of the torsion balance in which there are two parallel beams, connected by either four or six wires. The wire, F, carrying the secondary beam, E, and poise, H, instead of being carried on an independent support, rigidly attached to the base, as above described, is attached directly to a moving part of the balance itself, and preferably to the two beams. In Fig. 3, T T T are trusses over which are tightly stretched the wires, B B B. A A' are two beams rigidly clamped to the wires; t is another truss with stretched wire, F F¹. The upper wire, F', is attached by means of a flexible spring and standard, S, to the upper beam, and the lower wire is attached either directly or through a standard to the lower beam. The secondary poise, H, is rigidly attached to the truss, t. The secondary beam, E, is also rigidly attached to the truss, and acts as a multiplying beam. The secondary structure thus completely fills two functions: First, that of multiplying the angle of rotation and thereby increasing the apparent sensitiveness of the scale, and, second, that of overcoming the effect of change of level. The secondary beam may be dispensed with if a multiplier is not needed, and the secondary truss, t, with its standard and counterpoise, H, used alone to counteract the effect of change of level. Fig. 5 shows a modification of this extremely ingenious arrangement.--Engineering.

LINK BELTING.

[Footnote: From a paper read before the "Technischen Verein" of New York, May 28, 1887.]

By CHAS. A. SCHIEREN.

The old saying that "there is nothing new under the sun" may well be applied to leather link belting. It is generally believed that these belts are of recent invention, but that is an error. They are over thirty years old.

Mr. C.M. Roullier, of Paris, experimented that long ago with small leather links one and one-half inches long by three-quarters of an inch wide. These links had two small holes at equal distances apart, and were joined with iron bolts, which were riveted at the ends, thus making a perfectly flat surface, and in that way forming a belt entirely of leather links.

Mr. Roullier's idea was to economize; he therefore utilized the material left over from the manufacture of flat belting. He perfected his belt and came to this country in 1862, when he patented the article here and tried to introduce it. At first it produced quite a sensation, and many tests were made, but it was soon found that Roullier's belts were not suited to running our swift motion machinery, and they were therefore abandoned as impracticable.

Mr. Roullier then introduced his invention into England, where he met with some success, as his belt was better suited to English slow motion machinery.

These belts are now largely used in England, many good improvements have been made in them, and almost every belt maker in Great Britain manufactures them.

Mr. Jabez Oldfield, of Glasgow, has the reputation of making the best and most reliable link belt in Great Britain. He has also the reputation of being the originator of these belts. This is, however, an error, the credit of the invention belonging, as we have said, to Mr. Roullier.

Mr. Oldfield, nevertheless, has invented many useful machines for cutting and assorting the links. He has also introduced improved methods for putting the links together.

For more than twenty years after Mr. Roullier's visit, nothing was done with leather link belting in this country.

In 1882, however, Mr. N.W. Hall, of Newark, N.J., patented a link belt, composed of leather and steel links. His method was to place a steel link after every third or fourth leather one, in order to strengthen the belt. In practical use this belt was found to be very defective, because the leather links soon stretched, and thus all the work had to be done by the steel links. The whole strain coming thus upon the steel links, they in course of time cut through the bolts and thus broke the belt to pieces. So this invention proved worthless.

In 1884 a Chicago belt company obtained a patent on another style of link belt. In this belt all the little holes in the links were lined with metal, similar to the holes in laced shoes. This produced an effect similar to that produced by Hall's patent. The metal lining of the holes cut the bolts into pieces by friction and thus ruined the belt. Therefore this patent proved a failure also.

After all these failures it fell to our lot to improve these belts so that they may now be worked successfully on our American fast running machinery. During the past two years we have made and sold over five hundred leather link belts, which are all in actual use and doing excellent service, as is proved by many testimonials which we have received.

Our success with these belts has been so surprising that we think we have found, at last, the long looked for "missing link," not in "Darwinism," however, but in the belting line. We prophesy a great future for these belts in this country.

How have we attained such success? First: We found that Roullier made a mistake in using leather offal, as, in the links of an iron chain, if one link is weak or defective, the whole chain is worthless, so in link belts, if one or two links are weak or made of poor material, the whole belt is affected by them. It is therefore of vital importance that only the best and most solid leather be used in making the links; second, the leather must be made very pliable, but at the same time its toughness and tenacity must not be injured, or it will stretch and break.

FIG 1.

These things are of great importance, and are the principal reasons for the failures of all former efforts. The leather which Roullier used was stiff, hard, and husky. He believed that the harder the link the greater its tensile strength, but upon actual test this