342 SCIENCE PROGRESS 



be so by experiment ? " To which we reply, " No, we are not 

 quite satisfied, the proof by a null method cannot be considered 

 finally satisfactory but it is the best we have attained so far ; at 

 any rate it is better than your juggling with Time and defining 

 the second to suit yourselves, so as to contrive artificially not only 

 that you cannot measure any effect due to motion but that there 

 can never be any effect to observe." 



The change of shape caused by motion is at least a physical 

 result, predicted at present, subsequently to be verified. Whereas 

 the definition of a unit of time, in such a way as forcibly to 

 neutralise differences of speed in different directions — even 

 though the stationary medium is really drifting relatively past 

 a moving body — is not based on a discovery or suspicion of a 

 compensatory influence but is a tampering with fundamental 

 natural entities in an illegitimate and preposterous manner. 



Time and Space are separate entities ; the course of one 

 is not to be disturbed by supposed exigencies in the other. 

 The excuse no doubt is that they are both abstractions derived 

 from our direct sense of motion and speed. But abstractions 

 though they may be, they are either unreal or they are indepen- 

 dent and absolute — something over which we have no control, 

 into the conception of which no mere physical mechanism 

 can enter. 



If clocks go at a different rate according to the way they are 

 moving — as they may, by a shortening of the pendulum — that is 

 a definite assertion which may be stated and some day may be 

 tested. But the varying rate of a clock has no influence what- 

 ever on the Course of Time. Time is one thing, its measurement 

 is another ; the bad going of a clock is an affair of mechanics, not 

 of metaphysics nor philosophy. 



Nor in our judgment has the motion of a source any influence 

 whatever on the speed of light. Light travels through the ether, 

 not through matter ; whatever matter does, ether is stationary. 

 The only effect of moving matter is that which corresponds to 

 its known refraction and dispersion effects and into these motion 

 enters in a known way. 



"How then!" Opponents will say, "Are you going to uphold 

 the intelligibility of truly absolute motion — motion with respect 

 to no axes of reference or to anything whatever — motion in the 

 abstract, through the void ? " 



" No," we reply, " not so but motion through the ether. That 



