HYDRA ULIC PRESSES AND LIETS. 71
While these trials were going on, Messrs. Clark & Standfieldhad been directing their attention to the placing of steel lioopsround the cast iron presses. The practical diffieulty of gettingthe hoops over the hange of the press presented itself, and itwas decided to make the hoops at the joints with flanges like thetire of a wheel. To prevent this flanged tire from being draggedoff, a small projection was left on the body of the press, theheated tire was then passed over this, and, in cooling, it fittedtightly behind it. Messrs. Clark & Standfield acted upon along and interesting niemoir by M. Kraft, chief engineer ofthe Soeidte Cockerill, 011 the calculations for, and method ofeonstructing, these presses, and a trial segment was made by
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the Societe Cockerill, as shown in fig. 14. This was tried underliydraulic pressure, the expansion being measured by a thinstrip of metal put round the cast iron cylinder, and anotherstrip round one of the steel hoops. The two ends of each stripwere connected by means of a spring adjusted by a screw, andwere also joined to the short ends of a kind of proportionalcornpasses, set to a ratio of 12 to 1. By this means any slightopening of the ends of the Strips, caused by the expansion ofthe cylinders, was shown twelve times its actual size on thelong arms of the cornpasses. Owing to friction (which was,however, reduced to a minimum by lubrication) and otliercauses, the measurements were not absolutely correct, but the