CAST IRON. 



391 



where p is the internal pressure of the fluid, 



/ is the maximum tensile stress in the material, 



caused by this pressure, 

 R is the external radius of the cylinder, 



and r is the internal radius. 



The relation expressed by this equation is chiefly of 

 use in connection with the design of hydraulic cylinders 

 and pipes, and ordnance. 



Tests of specimen thick cylinders are sometimes made 

 in ordinary testing machines by filling them with a fluid 



FlG. 188. AUKAMiEMKNT OF IXTEXSIKIER IX THE OWENS COLLEGE 

 TESTING MACHINE. 



substance and forcing a ram in by placing the cylinder 

 between the compression plates of the testing machine. 



