454 A. deF. Palmer, Jr. — Apparatus for Measuring, etc. 



pressure was 4385 atmospheres. Below the yield point of the 

 steel the volume decrement of the substance under compression 

 is proportional to the angle through which the head of the 

 screw is turned, and hence the first five points in this figure lie 

 on a continuous curve without a point of inflection. At higher 



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pressures the twist of the screw and the shear of its threads 

 destroys the above proportionality and the remaining points 

 lie much lower than they would if the screw had remained 

 rigid up to the point of fracture. No method of accurately 

 determining the extent of the distortion of the steel between 

 the points of yield and rupture was at hand, but if, as is prob- 

 able, the shear of the threads was small, the above results show 

 that the twist was nearly two complete turns. 



Brown University, Sept. 20, 1898. 



