THE EMERY MACHINE. 93 



by means of friction gearing. The motion given to the 

 driving pulleys is further transmitted through spur and 

 bevel gearing to the four vertical screws B B, which, on 

 being rotated, move the lower crosshead A either up or 

 down, as may be desired. The lower end of the tension 

 specimen is held in steel wedge grips, carried by this cross- 

 head A, while its upper end is held by a similar set of 

 wedges in the upper crosshead C. This second crosshead 

 is supported on the ends of four vertical pillars I) D, set in 

 the corners of a square. These pillars are rigidly fixed to 

 a casting at their lower ends, and thus serve to transmit 

 the force applied to the upper crosshead to the first 

 measuring lever E. This is a lever of the second order, 

 with its fulcrum at K. The end of the long arm of this 

 lever is connected, by means of a short link in tension, to 

 the second lever F, which is also of the second order. This 

 again is connected by a long link to the short arm of the 

 third lever G, which is a lever of the first order. On this 

 last lever hangs the jockey weight H, whose position on 

 the lever determines the magnitude of the load on the 

 specimen. The jockey weight is moved along its lever by 

 means of ascrew, which is under electric control in such 

 a way that when the beam lifts, owing to excess of load, 

 the weight is set in motion and equilibrium restored. By 

 this means the whole system is automatically kept in 

 balance. 



When compression tests have to be made, a compression 

 block is attached to the under side of the movable plate 

 A, and the specimen to be crushed is placed between this 

 block and the table L, which serves to transmit the load to 

 the weighing levers. Similarly for cross-breaking tests a 

 V piece is fixed to the crosshead A, and the beam supports 

 to the weighing table L. 



The Olsen machine, as thus briefly described, may be 

 taken to be typical of most of the machines which are used 

 to any great extent in America, chief among these being 

 the machines of Riehle and Fairbanks. They are all made 

 in several sizes, to suit the kind of work for which 

 they are intended. Autographic gears are attached to 

 many of these machines, for the purpose of automatically 

 recording the results of the test as it proceeds. 



The Emery machine was originally invented by Mr. 

 A. H. Emery, for use in the U. S. Arsenal, at Watertown, 

 Mass. The makers are now Messrs. William Sellers and 

 Co., of Philadelphia. The great advantages possessed by 



