2o POPULAR SCIENCE MONTHLY. 



Action he has erected a consistent scheme of molecular physics in 

 which he finds an explanation of most observed facts. 



The discovery by Zeeman of the effect of a strong magnetic field in 

 triplicating or multiplicating the lines in the spectrum of a flame 

 placed in a magnetic field meets with an obvious explanation when we 

 remember that the effect of a magnetic field on an electron in motion is 

 to accelerate it always transversely to its own motion and the direction 

 of the field. Hence it follows that a magnetic field properly situated 

 will increase the velocity of an electron rotating in one direction and 

 retard it if rotating in another. But a linear vibration may be resolved 

 into the sum of two oppositely directed circular motions and accord- 

 ingly a magnetic force properly applied must act on a single spectral 

 line, which results from the vibration of an electron in such manner 

 as to create two other lines on either side, one representing a slightly 

 quicker and the other a slightly slower vibration. 



The notion of an electron or point charge of electricity as the ulti- 

 mate element in the structure of matter having been accepted, we are 

 started on a further enquiry as to the nature of the electron itself. It 

 is obvious that if the electron is a strain center or singular point in the 

 aether, then corresponding to every negative electron there must be a 

 positive one. In other words electrons must exist in pairs of such kind 

 that their simultaneous presence at one point would result in the 

 annihilation of both of them. 



On the view that material atoms are built up of electrons we have 

 to seek for a structural form of atom which shall be stable and equal 

 to the production of effects we find to exist. 



The first idea which occurs is that an atom may be a collection of 

 electrons in static equilibrium. But it can be shown that if the elec- 

 trons simply attract and repel each other at all distances according to 

 the law of the inverse square no such structure can exist. The next idea 

 is that the equilibrium may be dynamic rather than static. That an 

 atom may consist of electrons, as suggested by Larmor, in orbital 

 motion round each other, in fact that each atom is a miniature solar 

 system. 



Against this view, however, Mr. T. H. Jeans ('Mechanism of 

 Radiation,' Proc. Phys. Soc. Lond., Vol. 17, p. 760) has pointed out 

 that an infinite number of vibrations of the electrons would be possible 

 about each state of steady motion and hence the spectrum of a gas would 

 be a continuous one and not a bright-line spectrum. 



If we are to assume an atom to consist wholly of positive and nega- 

 tive electrons or point charges of electricity, Mr. Jeans has indicated 

 that we may obtain a stable structure by postulating that the electrons, 

 no matter whether similar or dissimilar, all repel each other at very 

 small distances. 



