1920 \ The Theory of Relativity 41 



The Theory of Eelativity. L. T. M. Nation, Apr. 11, 1912. 

 The Principal Concepts of Physics. W. F. Magie. Science, Feb. 23, 1912. 

 The Principle of Equivalence and the Notion of Force. C. A. Kichardson. 

 Nature, March 18, 1920. 



