256 Mr. L. 0. Jackson on a Mathematical Investigation 



The difficulty in such measurements is that any leakage 

 of charge off the insulation of the gold-leaf system produces 

 an error which tends to increase the result obtained for the 

 capacity. The leakage and the consequent apparent increase 

 of capacity will be greater at higher voltages. 



In modern electroscopes the insulation of the gold-leaf 

 system itself is so good that this leakage does not affect the 

 result appreciably, but in most of the methods of measuring 

 the capacity of the leaf system the insulation of the charger 

 also comes in and this is usually much less satisfactory. 

 Preliminary measurements show that at 10 volts the capacity 

 is 0*71, at 40 volts 0'73, and at 110 volts 078. 



In order to investigate this point more carefully by the 

 method described in this paper, I have constructed an electro- 

 scope without any charger, and work with this is in progress. 

 I have to thank Mr. V. H. Jackson for much helpful criticism 

 and advice. 



Physical Laboratory, 



Patna College, India. 



XXIII. A Mathematical Investigation of the Stability of Dr. A. 

 W. Stewart's Atom. By Leonard 0. J ackson, F.P. S. L. } 

 Science Scholar of University College^ Nottingham *. 



IN a recent paper (Phil. Mag. Oct. 1918) Dr. A. W. 

 Stewart set forth the structure of the atom from the 

 point of view of the physical chemist. This atom proved so 

 successful from the chemist's point of view as to distinctly 

 merit the attention which the author invites from physicists. 

 The atom, in its simplest form (the form treated in the 

 present paper), is as follows : — " At the centre of the structure 

 is a group of negative electrons travelling in closed orbits 

 which, for the sake of clearness, may be assumed to be 

 circular. Closely surrounding this negative group lies 



another series of orbits occupied by positive electrons 



These orbits are assumed to be circular also Further 



still from the centre, other [negative] electrons move in orbits 

 of an elliptical character, the ellipses being much elongated, 

 so that the electrons travel in paths like those of comets in 

 the solar system. " The figure given later will explain the 

 idea. 



The present paper is a mathematical investigation as to 

 the stability or otherwise of such an atomic system. The 



* Communicated by Prof. E. H. Barton, F.R.S. 



