(6149 
the formulae (17) and (18) are the same as the two first equations, 
given by LARMOR on p. 215. Further, it is there pointed out that 
in the result for the angle of rotation the quantities depending on 
the last terms of (17) and (18) disappear. Indeed 
1 1 UD 1 
aera eS at 
V U. ze Die 
whence 
zi 1 1 ) 
oo == — | — — — }. 
res Ds 
So far, I agree with LARMOR’s calculation. But, in coming to his 
conclusion, he has overlooked that the value of @ still contains the 
velocity of translation. This is seen by referring to (16) and (19). 
Using these, we find 
1 = (1 neg 1 Kit 1 __ Be 
) Nis Te ( F zi) 
1 Ig 
K 1 v i; 
ct cK' la 
sid 2 1? & (1 v ) ap 
= lt a) ee 
If the body were at rest, the velocities of the circularly polarized 
c Ci has 2 
rays would be —— and —_, if kK, = K — 722 The mean of these 
Ks Kos 
values, up to the first power of &, is 
WW 3 
K iz 
If we also take into account the relation (9) and the value 
| ee | 
a= 
T 
of the frequency, we find that (20) does not differ from my result, 
expressed in the equation (10). 
§ 7. In order to show that the rotation must be independent of 
the motion of the earth, Larmor adduces also the general consi- 
derations that are to be found in Chapter X of his work; from these 
the proposition may really be inferred, though not without an auxiliary 
hypothesis. As is well known, the theory of optical phenomena in 
moving bodies is simplified very much by the introduction, instead 
