Michelson-Moiiey Experivient. 365 



^lorley's negative result, llieir discussion really proved that the 

 Michelson-Morley experiment was not conclusive as to the relative 

 motion in question ; Michelson apparently accepted this point of 

 ^iew, as in his paper of 1897,^ he specifies the hypotheses : — 



(a) Independence of motion ; 



(b) The contraction hypothesis; 



(c) Influence of the earth on the ether at the distance appar- 



ently required by his experiments, 

 .as all about equally difficult to credit. 



During the next ten years, Larmor and Lorentz, working inde- 

 pendently, developed the mathematical consei|uences of a new 

 ►electrodynamic theory, in which the atoms of matter were regarded 

 as complexes of positive and negative electrons, capable of free 

 motion, in a medium which that motion left undisturbed. Larmor- 

 was the first to succeed in extending the computations of this theory 

 "to the second order of small quantities, and so to conclude — 



(a) That the contraction posited by Fitzgeraldj and Lorentz 

 TS'ould necessarily take place in matter constructed from such 

 ^toms. 



(b) That its magnitude would be independent of the chemical 

 nature of the moving matter. 



(c) That this magnitude would be numerically equal to half the 

 square of the astronomical Constant of Aberration; i.e., precisely 

 that required to account for Michelson and Morley's results. 



(d) That these results would consequently conW into line with the 

 positive results of other experiments as evidence for the equality, 

 within the limits of experimental error, of the earth's orbital 

 velocity with the relative velocity of the earth and the ether. 



Larmor 's result was often misunderstood at the time, as it was 

 supposed — though quite erroneously^ — to be dependent on his 

 .special theory of electronic structure; but its pertinence was some- 

 thing more than confirmed when Lorentz^ proved that the contrac- 

 tion was not a mere second approximation, but an exact result of 

 "their elect rodyn am ic theory. 



In aU probability these investigations would have been regarded 

 as conclusive, but for the reluctance, long felt by chemists and 

 physicists alike, to accept a purely electrodynamic theory of 



1 See note 2, supra. 



2 Aether and Matter, pp. 17;M76. 



3 Larmor had actually anticipated (I.e., p. 86) and \varnc<l his readers ay:ain.st t'.iis njisintcrpre- 

 tation of hi.s {general ar^-uincnt. 



4 Proc. Anjst. .Acad. (En<;li»h edition), ^i-i P- 8W. 



5 a 



