1916] on Polarized Light and its Applications to Engineering 581 



the discs, and carries the transparent ring to be stressed. The cup- 

 leather is itself so thin that a pressure of a few pounds per square 

 inch will burst it, but when the ring D is mounted upon it, even a 

 pressure of 2,000 pounds per square inch maj be applied with safety. 



To Pump. 



Cross-Section. 



Side Elevation. 



ToPu.yrp 



Side Elevation. Cross-Section. 



Fig. 4. — Peessuee Chambees foe Applying Fluid Peessure to the 

 Internal and Exteenal Boundaries of Rings. 



In the experiments described above, the ring had a thickness equal to 

 the interior breadth of the cup-leather, but a small percentage of the 

 total pressure is absorbed by this leather, and is not exerted upon 

 the ring. The experimental results must therefore be slightly lower 



