258 Prof. W. Peddie on the 



In Dr. Bohr's investigation the characteristic formula? 

 for series are deduced in a beautifully direct manner, on the 

 postulate of the existence of energy quanta, and in connexion 

 with Rutherford's modification of the type of atom in which 

 electrons are supposed to circulate in rings around a central 

 nucleus. This leads to the usual impossibility of reconciling 

 certain actions with the laws of ordinary dynamics and 

 electrodynamics. In such cases, without specification of 

 the details of a suitable new dynamics, merely on the ground 

 of transference of energy in quanta, very simple explana- 

 tions of fundamental phenomena in modern physics are 

 obtained. The value of the new ideas as a working hypo- 

 thesis cannot be denied. But behind all this procedure 

 there lies the root question whether or not the peculiarities, 

 so readily explained on the new ideas, cannot be explained 

 in terms of the ideas of the older physics as consequences of 

 structural conditions. For example, structural conditions 

 can account for the non-entrance, at ordinary temperatures, 

 of more than five of the freedoms of a molecule of a diatomic 

 gas in interchanges of energy amongst the molecules ; and 

 thus a violation of the doctrine of equipartition of energy 

 amongst the freedoms can take place without violation of 

 the laws of ordinary dynamics. Similarly, it may be that 

 structural conditions compel, in certain cases, the emission 

 or absorption of energy in quanta without the existence of 

 definite indivisible units of energy, and that they also intro- 

 duce a limitation on the effective phases or complexions 

 whose full presence is essential to the deduction of the law 

 of equipartition from the doctrine of chance in combination 

 with the Newtonian laws of motion. 



Sir J. J.Thomson has recently (Phil. Mag. Oct. 1913) de- 

 scribed an atomic mechanism which would account for many 

 of the peculiarities under discussion. Along with a radial 

 action, uniform in all directions round the atom, he postulates 

 another radial action confined to definite tubes. The ex- 

 pulsion of an electron is effected by the absorption of radiant 

 energy under the condition of resonance. The difficulty, 

 whatever it be, of explaining the necessary magnitude of the 

 absorption with resonance seems to exist, in this case, as 

 strongly as in others to which objection has been raised on 

 that ground. The primary purpose in introducing this type 

 of atom was to obtain a ready explanation of the smallness 

 of the amount of ionization produced, per unit volume of a 

 gas, by means of Rontgen rays. The type described below 

 possesses this property and yet enables us to retain the 

 notion of a continuous wave-front. In the former, the 



