134 THE ANATOMY OF SCIENCE 



to lead to the various equations of optics, nor 

 how the undulatory field, of which I have 

 spoken, proves to be only a sort of shadow, cast 

 upon space, of periodic changes occurring in 

 the emitting and absorbing atoms themselves. 



I shall, however, just mention a crucial ex- 

 periment which, though difficult, seems to be ex- 

 perimentally feasible. In the apparatus shown 

 in Figure 22 let us suppose that C is the center 

 of a dark interference band and D is the center 

 of the next bright band. According to all 

 former theories, the light falling upon the mir- 

 ror AA' produces thereon a uniform pressure; 

 but according to the new theory no corpuscles 

 are striking the end A' while many strike the 

 end A. The mirror therefore, if supported by a 

 fine suspension, would tend to rotate about its 

 center. 



If such a rotation can be observed it will con- 

 stitute powerful evidence for a theory which not 

 only is in full harmony with our relativity ge- 

 ometry, but also removes the last foothold in the 

 physical sciences of the concept of temporal 

 causality. 



