1919] on Ether and Matter 461) 



The atoms of different elements differ in the number of positive 

 units in the nucleus, and in the corresponding number of revolving 

 negative units ; in fact the diverse chemical elements, in their atomic 

 constitution, form a definite arithmetical series with common differ- 

 ence one. There is a discontinuity or finite step in passing from 

 one element to the next in the series, there is no continuous passage 

 from one to another ; hence if the physical transition or mutation 

 ever occurs, it must be by some sort of sudden convulsion. 



To extract laws for this hypothetical structure, suggested by the 

 labours of many workers, we may attend to the different rings of one 

 kind of atom, or we may attend to the corresponding rings in 

 different kinds of atom. Each, for instance, has an innermost ring, 

 which it is convenient at present to call the K ring, because of the 

 shortest wave lengths, or so-called K spectrum, which its perturba- 

 tions emit. And, in ascending the series of elements, as the nucleus 

 gets stronger by addition of units, the electron in this innermost or 

 K ring must revolve faster and faster to counterbalance the greater 

 attracting force. Its orbit will accordingly get smaller and smaller, 

 in the proportion proper to the law of inverse square. And the 

 frequency will increase for both reasons, i.e. for both the greater 

 speed and the shorter journey. The spectrum accordingly, while 

 preserving the same type, ascends the ladder of frequency. 



Suppose the atomic number, or strength of the nucleus in atoms 

 of successive elements, increases in arithmetical progression N - 1, 

 N, N -1- 1, etc., then the radius of the given type of orbit may 

 shrink in the same proportion, so that r X is constant ; and the 

 velocity v may increase in the same proportion, so that r v is con- 

 stant ; or in other words so that the moment of momentum in 

 corresponding rings of different atoms is the same. There is good 

 evidence that such is the case. The law, so far as it is a law, is 

 styled by Professor Millikan, the atomicity of angular momentum. 

 If the value of mvr or mr-w differs in different rings, it differs 

 by finite steps. 



The frequency of orbital revolution will depend on v directly 

 and on r inversely, so the frequency [vj^-rrr) will increase in the 

 proportion of N^ ; and this, in some form or other, is known as 

 Moseley's law. 



The energy, \ m v- in a given type of ring, will also depend upon 

 N- in different atoms, and is therefore simply proportional to the 

 frequency. The orbital energy is half the energy with which a 

 particle breaks loose (or is driven to infinity) whenever a convulsion 

 occurs. The convulsion can be stimulated by X-rays or ultra-violet 

 light of the right frequency ; their energy appears to be stored by 

 resonance until the critical breaking-up point is reached. The ratio 

 of emission energy to frequency is a remarkable universal constant, 

 and is called h, the quantum. It is not energy, but the accumula- 

 tion or integral of energy for a certain time ; and it is permissible to 



