APP. L.] DUE TO HIGH SPEED 227 



cisely zero resultant, in the Michelson experiment, but 

 that the change was a necessary consequence of dynamical 

 molecular theory. 



The change of dimensions, thus imagined and justified, 

 is gradually coming to be accepted as certainly true; 

 and it is interesting to note that a sphere in motion, 

 by reason of being subject to this amount of distortion, 

 still retains its property of being the simplest geometrical 

 body, so far as the distribution of its electric field is con- 

 cerned. True, it is then no longer a sphere ; but no 

 measuring instrument could possibly show its distortion, 

 because all standards of measurement would share it. It 

 is a remarkable thing that this imperceptible and un- 

 rneasurable uniform distortion of all matter should ever 

 have been discovered : nothing but an ethereal process 

 could have dragged it to light. Nevertheless dragged to 

 light it has been, by the combined testimony of electrical 

 theory and of optical experiment. 



APPENDIX M. 

 Constitution of Electrons. 



In continuation of the subject treated of in appendices 

 K and L we may consult Larmor, Phil. Trans. 190A 

 (April, 1897), pp. 225-8. In ^Ether and Matter (1898), 

 ch. xi., he substituted an improved (dynamical) investiga- 

 tion, applicable to a system of molecules in the most 

 complicated motion, wherein he claims to cover all 

 possible cases, on the single hypothesis that the electrons 

 in an atom are at distances apart compared with which 

 the diameters of their structure are very small, so that 

 they may be treated as points. On that hypothesis 



