[ n ] 



IX. The Negative Results of Second and Third Order 

 Tests of the "Mther Drift," and Possible First Order 

 Methods. By D. B. Brace* 



PROFESSOR LAEMORt in his analysis for a system 

 moving through the aether has shown how first and 

 second order effects may be annulled in certain optical and 

 electrical tests of the aether drift. He has not shown, how- 

 ever, how to annul third and higher order effects ; but he 

 states, " if indeed it could be proved that the optical effect is 

 null up to the third order, that circumstance would not 

 demolish the theory, but would rather point to some finer 

 adjustment than it provides for : needless to say the 

 attempt would indefinitely transcend existing experimental 

 possibilities" %. 



Attention should therefore be called to the results in my 

 experiment on the double refraction of water moving through 

 the aether. The sensibility attained was such that " the 

 greatest difference in velocity or in index between the two 

 components which could exist, referred to that of water for 

 green light, \ = '00005 cm., was less than 7*8 x 10~ 13 of the 

 whole. If (10 _4 )§ be taken as the third order magnitude, 

 this result is then easily within the limit. It was not pos- 

 sible to attain this sensibility with a solid — glass; but, since 

 the physical state of the substance does not enter into the 

 theory under consideration, the results for a liquid should be 

 equally valid. 



The conclusion as to the amount of double refraction as 

 deduced from what might be expected in comparison with 

 accidental double refraction in a solid — glass, should not be 

 considered as defining the mode and the amount of any 

 double refraction arising from molecular reactions due to a 

 system moving through the aether. 



Granting the FitzGerald-Lorentz " contraction-hypothesis," 

 we should have for this experiment a complete correspondence 

 as regards molecular activities between the moving system 

 thus shrunk and the same at rest, up to and including second 

 order quantities, as the analysis of Larmor shows. But the 

 negative results of such a third order test, showing as it does 

 the absence of any difference between the moving and the 

 fixed system, up to and including third order quantities, may 



* Communicated by the Author. Read in part "before Sect. B, Amer. 

 Assoc, for Adv. Sci., Philadelphia Meeting, 1904-5. 

 + ' ./Ether and Matter/ Chap. xi. 

 X Phil. Mag. June, 1904, p. 624. 

 § Phil. Mag. April, 1904, p. 818. 



