XVI. 3] SPINNING ELECTRONS 223 
to that of a rigid body. The final result found gives the energy as 
T = me 2 + |(Aft)! 2 + Bco 2 2 + Ca> 3 2 ) + constant 16 : 1 
In the first term m = m 0 /( 1 — /l 2 ) 172 where m 0 — \e 2 /ci and 
p —v/c. The components of spin are (o x , co 2 , co 3 , and the 
electrodynamic moments of inertia may, in general, be expressed 
in the form 
A=I(i+«i/3 2 +« 2 ^ 4 + • • )> B=C=I(i+c 1 jS 2 +c 2 iS 4 + . . ), 
where I = \m a a 2 is the moment of inertia of the spinning electron 
at rest. 
It appears probable that the boundary conditions adjust 
themselves so that the interior fields of the electron remain 
unchanged at the velocity under consideration. This assumption 
leads to the classical expressions for the force on an electron in 
an electric or magnetic field. 
The spinning or gyrostatic electron moving with uniform 
velocity under no forces has a single precessional frequency v 
given by 
2nv=Q x (C—A)/C=Q 1 (c 1 —a 1 )p 2 (i+b 1 fi 2 +b 2 p i + . . .) 16:2 
where Q x is the constant intrinsic spin of the electron. 
Fitzgerald has shown that an oscillating magnet can radiate 
electromagnetic waves, so that v may be regarded as the frequency 
of the emitted radiation. 
If we put 
hQ x — nc 2 m 0 /(c x — a x ) . . . . 16 : 3 
where (c x — a x ) is a numerical constant equal to 2/5 for the 
simple model considered, we find to a first approximation : 
hv — \m Q v 2 16 : 4 
the well-known photo-electric equation. 
Planck’s constant then appears as a quantity characteristic 
of the spinning electron, and dependent on its intrinsic spin. 
It is claimed that with similar hypotheses as to spinning 
protons the series formula for line spectra can be deduced, and 
the correct value for the Rydberg constant obtained. The photo 
electric equation used in conjunction with a Maxwellian dis 
tribution of electron velocities, also leads, with reasonable hypo 
theses as to electron orbits in a space lattice, to Planck’s formula 
for black-body radiation and the associated formulae for specific 
heats. 
Although objections may be raised against certain features of 
the exposition, the attempt is interesting as indicating that there 
are still possibilities in the construction of models which in 
certain respects conform to the classical laws. There remains the 
difficulty of accounting for an intrinsic spin which is to be the 
same for all electrons.