10 THE ROYAL SOCIETY OF CANADA 



opened up new regions.* It appears that negative electricity consists 

 of electrons with their accompanying but unexplained effects in the 

 ether. Electrons in motion produce magnetic fields. Their effective 

 mass is about one eighteen hundredth part of that of a hydrogen 

 atom, and their effective radius one hundred thousandth. The 

 greatest known speed of electrons nearly approaches that of light. 



The Zeeman effect, or separation of a single line in the spectrum 

 by suitable magnetic fields into two or more lines, proved conclusively 

 that the vibrations of negative electrons in the atom are the cause 

 of the disturbances in the ether which we know as light. 



(4). The first scheme of an electronic atom, propounded by Sir 

 Joseph Thomson, was a sphere of positive electricity, of undefined 

 character, within which revolved concentric rings of electrons in the 

 same plane. There necessarily followed the simplicity of circular 

 motion under a force to the centre proportional to the distance 

 between the electron and the centre of the atom. 



(5). Previous to this Lord Rayleigh had called attention to a 

 serious anomaly. In a train of waves of a periodic character, the elec- 

 tric intensity E varies as the sine of nt, where t is the time and 2^jn is 

 the period. As the equations involve the second differential of E, 

 it appears inevitable that the square of n should appear in spectral 

 series. As a matter of fact there appears not the square of n, but n 

 itself. It is desirable to be more explicit. If parallel light from a 

 luminous source passes through a slit and a prism, together with suit- 

 able lenses, then the eye or photographic plate can detect a number 

 of bright lines forming the spectral images of the slit for different 

 colours, provided that the source of light is luminous mercury vapour 

 or hydrogen, or some such luminous gas. Many of these lines have 

 been found to belong to one or more series crowding together towards 

 the violet end. Balmer and Rydberg have found that the general 

 type of formula for this frequency n is, 



n=N i^-i) 



where N is a universal constant called Rydberg's number, the same in 

 value for all electrons of all atoms; and a and b are whole numbers 

 or integers. We shall refer later to the importance of Rydberg's 

 constant and of this magnificent generalization. 



The trouble to which Rayleigh referred was first faced by Ritz 

 in a startling manner. He imagined that there were inside the atom, 

 *It is remarkable how little the general public has shared in this advance. In 

 Montreal there were eleven thousand people witnessing a wrestling match while 

 few availed themselves of an invitation to meetings and discussions of the Royal 

 Society. 



