214 Proceedings of the Eoyal Society of Edinburgh. [Sess. 
in which the electron is revolving about an inner nucleus consisting, 
for example, of a positive ion. . . . Since the system creates an atomic 
magnetic field the axis of which passes through the centre of rotation 
of the electron and perpendicular to the plane of rotation, the speaker 
suggested calling such systems ' magnetons.’ ” ^ The word was used 
independently by Professor Gans and Professor Weiss, but it should be 
observed that the magneton of Weiss is an empirical and not a mechanistic 
deduction, and its existence is not demonstrated with certainty. 
In 1913 S. B. McLaren * * * § [- discussed the properties of a magneton, 
regarded as an inner limiting surface of the sether, formed like an anchor 
O O'' 
ring. Tubes of electric induction terminating on its surface give it an 
electric charge ; tubes of magnetic induction linked through its aperture 
make it a permanent magnet. This form of magneton seems to be 
specially adapted to the four-dimensional analysis of Professor Whittaker. 
In 1915 A. L. Parson f put forward a magneton theory of the structure 
of the atom, in which the magneton, or ring electron, was looked upon 
as a thin circular anchor ring of negative electricity rotating about its 
axis with large velocity. Assuming that the angular momentum of the 
ring electron (charge e, mass m) has the value /i/27t appropriate to the 
quantum theory, its magnetic moment, J(e/m)(/i/27r), is found to be 
9‘232 X 10 E.M.U.§ The structure in the atom postulated by Sir Alfred 
Ewing II in his recent models of ferromagnetic induction is obviously 
composed of magnetons, and it is interesting to notice that the magnetic 
moment of the rotatable Weber element in each atom of iron is found 
to be nearly 2 x 10"^® E.M.U., or about twice the above value. 
The mechanism imagined by Professor Whittaker for the absorption of 
energy from the electron must also be described as a magneton, if we use 
that term in the wide sense advocated above. It is true that at the end 
of § 3 of his paper it is suggested that the model, having served its purpose, 
may be allowed to drop out of sight, and that the “ magnetic structure ” 
which suggested the equations need not be insisted on. But in view of 
the fact that Professor Whittaker is prepared to retain the electron, and 
in four dimensions is prepared to place magnetic forces on an equality with 
electric forces, it must surely be necessary to retain in three dimensions 
* Science, vol. xxxi, p. 920, June ]0, 1910. 
t S. B. McLaren, Association Beijort, 1913; Phil. Mag., ~wo\. xxvi, p. 800, 1913 ; 
Nature, vol. xcii, p, 165, 1913. 
I A. L. Parson, Smithsonian Misc. Goll., vol Ixv, No. 11, 1915. 
§ H. S. Allen, Phil. Mag., vol. xli, p. 119, 1921. 
II Sir J. A. Ewing, Proc. Roy. Soc., vol. c, p. 449, 1922 ; Phil. Mag., vol. xliii, p. 493, 
1922 ; Proc. Roy, Soc. Edin., vol. xlii, p. 97, 1922. 
