580 



Professor Ernest G. Coker 



[Feb. 18, 



Showing a fair agreement with the theory, which is really closer than 

 the numbers indicate, owing to the full pressure recorded on the 

 gauge not being effective, as will now be described. 



As is evident, this stress problem requires the application of 

 a measurable fluid pressure to the cylindrical surface of a ring, in 

 such a way that no essential part is obscured from view, and a simple 



and effective means has been devised for this purpose by my assistant, 



Mr. F. H. Withycombe. 



Fig. 3. 



Fig. 8 is a photograph of the complete apparatus for applying 

 internal and external fluid pressure to rings, and drawings of the 

 essential details are shown in side elevation and cross section in 

 Fig. 4. ^ 



Fluid pressure of water or other hquid is applied by the action 

 of a small hand-pump P, the piston of which is actuated by a screw 

 to force oil at any desired gauge-pressure into the annular space 

 between two metal discs A, B, bolted together to hold a retaining 

 ring C shaped like a Bramah cup-leather to prevent leakage of the 

 fluid. This retaining ring projects slightly beyond the periphery of 



