VIII. 5] WHITTAKER’S QUANTUM MECHANISM 117 
integral number of times the fundamental quantum tube defined 
by h/e, in exact agreement with previous results. 
It may be noted that the angular momentum is independent 
of the size of the magnetic wheel. 
The general arrangement of the lines of magnetic force in 
the model is not unlike that which would occur if two thin anchor 
rings, representing the magnetons either of McLaren or of Parson, 
were placed near together with their planes parallel and having 
a common axis. Thus, if we think of Whittaker’s magneton as 
a bicycle wheel, these rings would be represented by the two 
beaded edges of the rim. But to obtain the required distribution 
of the lines of magnetic force the rings must be placed so that 
the magnetic force between them is one of repulsion ; con 
sequently the currents in these rings would be in opposite 
directions. 
Whittaker has pointed out that the two ring electrons with 
opposed currents, described above, would be equivalent to a 
magnetic shell forming the curved surface of a cylinder, having 
its edges coincident with the two rings. 
This model is open to the objection which Eldridge brought 
against the original model. With regard to such a suggestion 
Lorentz makes the comment : “It might seem at first sight that 
in a structure of this kind the magnets can be replaced by 
perfectly conducting solenoids carrying pre-existent electric 
currents, so that we can do without magnetic charges. 
“ In reality, however, no satisfactory model can be obtained 
in this way. This is seen most easily when the electron is supposed 
to move along the axis OX. In the magnetic field due to this 
motion the lines of force are circles around the axis, and therefore 
the line of force acting on an element of current at a point P 
is directed along a line lying in the plane POX. For such a point 
the moment with respect to OX is zero ; consequently, neither a 
solenoid nor a system of solenoids can be acted on by a couple 
tending to produce a rotation about OX. 
“ Thus it would seem that the hypothesis of ‘ magnetism ’ 
existing independently of electric currents is quite essential to 
Whittaker’s model. I need not speak at length of the reasons 
for which such an assumption is not to be readily admitted.” 
(2) In dealing with the transformation of energy into the 
radiant form Whittaker discards the magnetic wheel and deals 
with a Hertzian oscillator. It is important to notice that when 
he introduces a natural constant of action, he is departing from 
classical theory and postulating a vibrator which does not lead 
to the law of equipartition of energy. 
At first sight Whittaker’s choice of h/n as the value of the 
natural constant e 2 \/(L/C) seemed somewhat arbitrary, and