60 Presidential Address 



It is the extreme omnipresence and 

 uniformity and universal agency of the 

 ether of space that makes it so difficult to 

 observe. To observe anything you must 

 have differences. If all actions at a dis- 

 tance are conducted at the same rate 

 through the ether, the travel of none of 

 them can be observed. Find something 

 not conveyed by the ether and there is a 

 chance. But then every physical action 

 is transmitted by the ether, and in every 

 case by means of its transverse or radi- 

 ation-like activity. 



Except perhaps Gravitation. That 

 may give us a clue some day, but at 

 present we have not been able to detect 

 its speed of transmission at all. No plan 

 has been devised for measuring it. No- 

 thing short of the creation or destruction 

 of matter seems likely to serve: creation 

 or destruction of the gravitational unit, 

 whether it be an atom or an electron or 

 whatever it is. Most likely the unit of 

 weight is an electron, just as the unit 

 of mass is. 



The so-called non-Newtonian Median- 



