THE ZEEMAN EFFECT AND DISPERSION. 423 



we have supposed magnetic force to have on the vibrations 

 as being: a rotation of all linear vibrations round the lines 

 of magnetic force, or a precessional rotation of the axes of 

 the vibration, in the case of non-linear vibrations. Lorentz 

 has pointed out that if the vibrations in matter that are 

 connected with the ether are due to the motions of electrons, 

 this very precessional motion is what might be expected 

 from the disturbance of the orbits of the electrons by the 

 magnetic force. We may then reasonably expect that 

 magnetic force does make the right-handed circular com- 

 ponent of the vibrating molecules to rotate at a different 

 frequency from the left-handed component, these components 

 rotating round the lines of magnetic force. Hence, one of 

 these components in the ultra-violet vibration that controls 

 disperson will become more nearly of the same frequency 

 as that of visible light and so will cause the corresponding- 

 circular component of the visible light to be propagated 

 more slowly than the oppositely rotating component, — for 

 this latter will be less in accord with its corresponding- vibra- 

 tions in the molecules when magnetised than when there 

 was no magnetic force acting, and so will be less affected by 

 them. Hence there would seem to be every reason for 

 attributing the Faraday effect in diamagnetic bodies to such 

 a change in the vibrations of the molecules as has been 

 described. When we consider the observed direction of 

 the Faraday effect in diamagnetic bodies we find that in 

 order to explain it by Lorentz's theory we must assume 

 that the connection between matter vibrations and the ether 

 is principally due to the motion of a negative electron. This 

 is no doubt a very remarkable deduction from the theory, 

 but some phenomena of vacuum tube discharges seem 

 to imply that the negative electron is more free to move 

 about than the positive electron. This may all be due to 

 some essentially positive characteristic of the matter in our 

 part of the universe. The accumulation of matter of the 

 same kind in one system being possibly produced by its 

 gravitational repulsion for matter of the negative character. 

 And now what independent evidence is there that 

 magnetic force can influence the vibrations of molecules? 



