1 22 Presidential Address 



primary foundation for the Principle of Relativity. The 

 Principle goes on to translate difficulty, in the first case, into 

 impossibility, and then to make elaborate mathematical 

 deductions. 



The mode in which I would explain the admitted fact 

 that nothing but relative motion of pieces of matter has so 

 far been observed, is indicated on pages 47 et seq.; the cause 

 of all the negative experimental results, on which founda- 

 tion of the Principle rests, is to be found in the complete 

 uniformity of the ether and in its universal activity and 

 prevalence. This has led to the Principle which virtually 

 denies its existence. The last thing that a deep-sea fish 

 could discover would be water. (See also page 106.) 



Page 46 



The second paragraph on this page is another refer- 

 ence to my Ether-gripping experiment, referred to in the 

 above note and page 35, and briefly described in my book 

 The Ether of Space. The word " hope " can only be used 

 in a special sense in connection with any experiment: the 

 object of that experiment was of course to ascertain 

 whether the ether is to any degree attached to moving 

 matter or not. I was not aware of having any expectation 

 of a positive result. What I was anxious about was to 

 make sure of a definite answer one way or the other. 



Page 49 



Rotation of an isolated non-rigid body can be detected 

 by its bulging under centrifugal force: as when a bucket is 

 twisted the liquid surface becomes parabolic. Again, the 

 non-spherical shape of the earth or of Jupiter is immedi- 

 ately connected with their periods of rotation, i.e., with 

 the length of their respective "days. The oblateness of the 

 earth was thus quantitatively predicted by Newton long 



