CLASSICAL AND NEW MECHANICS 185 



postulate will be accepted for all mechanical motions 

 and no further attempts should be made to find experi- 

 mentally an absolute motion. But the second postulate 

 contradicts the principle of relativity, if by V we mean 

 the absolute motion of something, matter, energy, 

 or light through quiescent space. If, on the other 

 hand, V is understood to be the velocity of light in 

 space containing matter, then it cannot be taken as 

 a universal constant. The third postulate concerning 

 time should not cause us to change our belief that the 

 dimensions of a body and the unit of time are inde- 

 pendent of velocity, but it should show us how to cor- 

 rect our measurements of moving bodies, as we must 

 correct all subjective measurements of objective phe- 

 nomena. 



If we grant the assumptions of Professor Einstein, 

 the theory of relativity is a perfectly logical system so 

 long as we apply it to abstract systems moving with a 

 constant velocity in a straight line. But I can find no 

 evidence that the postulates agree with experimental 

 facts and certainly, to the present time at least, its 

 conclusions will not affect experimentally the laws of 

 mechanics. Also its theoretical conclusions are limited, 

 as yet, to the rare cases when there is neither any 

 change of speed nor of direction. We should remem- 

 ber before we abandon or modify Newtonian mechanics 

 that mathematicians have devised numerous systems 

 which point to different mechanical laws. If we pos- 



