222 Proceedings of the Eoyal Society of Edinburgh. [Sess. 
This enables us to calculate the radius of the magnetic orbit. If we 
assume, (i) that i/ is the frequency of Na yellow, and (ii) that it is the 
o 
frequency corresponding to 1 Angstrom unit in the X-ray region, we obtain 
respectively a = 2'7 x 10“^ cm. and a = 3*5 x 10“^^ cm. As the diameter of 
a hydrogen molecule is about 2x10”^ cm., the first value is on the high 
side. But it is very satisfactory considering the simple nature of the 
assumptions made ; it will doubtless be possible to devise a more elaborate 
rotating system o£ smaller dimensions which will at the same time make 
the vibrations isochronous throughout a wider range. 
It will be noticed that according to equation (4) the radius of the 
magnetic orbit varies inversely as the root of the frequency. This is in 
agreement with the view advanced towards the end of the paper, namely, 
that the oscillators are always of the same type but differ from one another 
in scale. 
If 1 / be eliminated between (2) and (3), 
27t(X J(mA) 
= jmey. numerical factor. 
This numerical factor becomes ir, if the rotating system is a single magnet 
of moment of inertia muA Thus Planck’s constant comes out as the product 
of the unit electric charge and a unit magnetic quantity ; this has, of 
course, the correct dimensions. It consequently follows that there must 
be some truth in the view that there is a unit tube of induction. 
Hitherto in dealing with atomic models we have always assumed that 
the play was between kinetic energy of moving electrons and electrostatic 
potentiad energy. Apparently the latter must now be replaced by the 
kinetic energ}^ of moving magnets ; potential energy disappears from the 
scheme altogether. At the same time the reciprocity which exists between 
electric and magnetic quantities in the electromagnetic wave must be 
extended to atomic structure. 
The new quantum mechanism is of the highest importance both for the 
vistas it opens out and the salutary influence it will exert on some of the 
more speculative theories of radiation. 
{Issued separately July 4, 1922.) 
