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THE QUANTUM [xvi. 3 
have not as yet been fully investigated, but it must be remembered 
that these were implicit in the magneton of A. L. Parson and 
were taken for granted in the static models of Lewis and Lang 
muir. It need only be said here that the difficulties of explaining 
the diamagnetic properties of hydrogen and helium when the 
Bohr model is employed, disappear on the introduction of electrons 
which possess magnetic moment. 
The remarkable results obtained by employing the spinning 
electron in Bohr's atomic model suggest the idea that the proton 
also may be capable of a quantized spin. If, as is generally 
assumed, the proton is the positive electron, it seems natural 
to assume that if the negative electron can spin with unit angular 
momentum the positive may do the same. Again, it may be 
easier to understand the structure of a complex nucleus if the 
units of which it is composed can act as elementary magnets. 
Duane * has attempted to explain corpuscular emission from a 
radioactive nucleus on these lines. According to O. W. Richard 
son, f it is probable that the electron loses its angular momentum 
when it enters into the nucleus, but the magnitude of the 
mechanical gyromagnetic anomaly makes it necessary to admit 
the existence of a quantized spin of the nucleus as a whole. 
Finally experiments on the deflection of protons and alpha 
particles in collision with an atomic nucleus lend support to the 
idea that a magnetic field exists in the vicinity of a nucleus. 
3. The Gyromagnetic Electron of L. V. King 
A rotating spherical charge sets up a magnetic field, which 
was investigated by Maxwell in 1870. The internal field is uniform 
and of strength §eoo/a, while the external field is that of a mag 
netic doublet of moment |ecoa 2 , where co is the angular velocity 
and a the radius of the sphere. 
A simple type of spinning electron based on Maxwell’s work 
has been discussed by L. V. King,! who has attempted to give 
a theory of atomic structure and radiation by using classical 
electrodynamics. His work is of great interest, and although it 
obviously cannot claim finality, the attempt shows that the 
resources of classical theory have by no means been exhausted. 
When the spinning electron is moving in a specified direction 
with velocity v, it is deformed by translation into an ellipsoid, 
the short axis being in the direction of motion. Regarding this 
as a real, physical deformation, the total energy of the field due 
both to translation and to spin, including the work done by the 
boundary stresses (probably magnetic in origin) is similar in form 
* Duane, Phys. Rev., vol. 5, p. 335, 1915. 
t Richardson, Nature, vol. 117, p. 652, 1926. 
t L. V. King, Gyromagnetic Electrons (Louis Carrier, Montreal, 1926).