64 Presidential Address 



both are active, and they nearly balance 

 At anything but molecular distance they 

 quite balance, but at molecular dis- 

 tance attraction predominates. It is the 

 diminution of the predominant partner 

 that will be felt. Hence while longi- 

 tudinal cohesion, or cohesion in the direc- 

 tion of motion, remains unchanged, lateral 

 cohesion is less ; so there will be distortion, 

 and a unit cube x y z moving along x with 

 velocity u becomes a parallelepiped with 

 sides i/k 2 , k, k; where i/k 6 = i - u 2 /v 2 . ' 

 The electrical theory of matter is a 

 positive achievement, and has positive 

 results. By its aid we make experiments 

 which throw light upon the relation be- 

 tween matter and the Ether of Space. 

 The Principle of Relativity, which seeks 

 to replace it, is a principle of negation, a 



1 Different modes of estimating the change give slightly 

 different results; some involve a compression as well as a 

 distortion in fact the strain associated with the name of 

 Thomas Young ; the details are rather complicated and this 

 is not the place to discuss them. A pure distortion, as 

 specified in the text, is simplest, it appears to be in accord 

 with all the experimental facts including some careful 

 measurements by Bucherer, and I rather expect it to 

 survive. 



