526 Dr. H. Stanley Allen on 



But \dt is the period of revolution, and =l/v. 



Hence N m £ = nh, 



or as in (1) N m =n(/ije). 



3. In my paper read before the Royal Society of Edin- 

 burgh, I have shown how this result may be extended to the 

 case where any number of point charges are revolving round 

 an axis with a common angular velocity. Such an arrange- 

 ment might be taken as representing an atom in one of its 

 steady states. The various results may be summarized by 

 saying that the number of magnetic tubes passing through 

 the aperture of the magneton, or through the stationary 

 circular orbits of the revolving electrons, is equal to an 

 integer, ?i, multiplied by the constant factor kje. The 

 simplest way of interpreting this is to suppose, with Faraday, 

 that magnetic curves may be considered as discrete physical 

 entities. The quantity 



h/e 



may be regarded on this view as defining what must be the 

 fundamental unit magnetic tube. 

 Taking 

 A = 6'558xl0- 27 erg see. and <? = 4'774 x 10" 10 E.S.U., 

 the unit magnetic tube of: induction is equal to 



1-374 xlO" 17 E.S.U. or 4-120 X lO"' E.M.U. 



Consequently one C.G.S. magnetic tube (one maxwell) 

 contains 2*43 X 10 6 quantum tubes. 



4. An electrodynamic interpretation of Planck's constant, 

 h, was suggested in 19 L6 by A. L. Bernoulli * ? who came to 

 the conclusion that when electrons are in movement in a 

 molecular magnetic field, the number of lines of force cut 

 by the radii vectores at each revolution is one and the same 

 universal constant. In other words, all the electron reso- 

 nators are traversed by a like universal tube of magnetic 

 force. Bernoulli's treatment, however, cannot be con- 

 sidered satisfactory, since he makes the assumption that the 

 molecular magnetic field may be regarded as uniform. That 

 this assumption must be far from the truth is shown by 

 considering the results in my former paper dealing with the 

 ring electron f or the work of Oxley % on the molecular 

 magnetic field. 



* A. L. Bernoulli, Archives des Sciences, vol. xlii. p. 24 (1910). 

 t H. S. Allen, Phil. Mag. vol. xli. p. 113 (1921). 



t A. E. Oxlev, Phil. Trans, vol. ccxiv. p. 109 (1914); vol. ccxv. 

 p. 79 (1915) ; vol. ccxx. p. 247 (1920). 



