CHAPTER XVI 
SPINNING ELECTRONS 
Without any assertion of finality in the description of electronic 
interactions by its means, the importance of the spinning model of 
the electron can scarcely be overestimated. Yet the spinning elec 
tron has been so lost in the far wider ideas embodied in the new 
mechanics that it is as yet scarcely appreciated at its full value. . . . 
The spinning electron has brought order out of chaos in the 
broad outlines of atomic theory. Its necessity and its successes are 
qualitatively independent of the new mechanics. 
R. H. Fowler, Nature, January 15, 1927 
1. Early Work on Spinning Electrons 
HE conception of a rotating electron has been suggested by 
1 many investigators. Reference may be made to the work 
of Voigt (1902), and of Abraham (1903), and it is of interest to 
notice that Ritz in his magnetic model of 1908, in which he 
attempted an interpretation of spectral series, definitely put 
forward the idea that his elementary magnets might be composed 
of electrically charged bodies rotating about an axis. McLaren 
in 1913 described a magneton which was endowed with an 
angular momentum of amount h/271. It is true that in one sense 
this magneton cannot be described as a spinning electron, for 
McLaren rejected entirely the idea of electric or of magnetic 
substance, and supposed that the angular momentum of the 
magneton was to be found in the electro-magnetic field. The 
essential fact remains that McLaren first postulated a physical 
unit endowed with the quantum of angular momentum. 
In a discussion on the structure of the atom at the Royal 
Society on March 19, 1914, in referring to the magnetic moment 
of the magneton, the author * made a tentative suggestion that 
the core of an atom might be regarded as a revolving sphere of 
positive electricity, or, alternatively, that the electron might be 
a revolving sphere of negative electricity. 
Another type of spinning electron is the magneton or “ anchor 
ring ” electron of A. L. Parson (1915) in which a ring of negative 
* H. S. Allen, Nature, vol. 92, p. 713, 1914 ; Phil. Mag., vol. 29, 
p. 714, 1915.