eviii Proceedings of the Asiatic Society of Bengal. [N.S., XV, 
As to the properties of iain field, there is one fact that is 
RO her known e medium does take part in the transfer- 
ence of energy, a and so doe the luminiferous medium through 
which the vibratory energy of which light is known to consist 
is transmitted from the source to the eye of the observer. 
Are the two mediums identical ? Since the velocity of propaga- 
tion of an electromagnetic disturbance (of which an oscilla- 
tory discharge is the source) is equal to the velocity of propaga- 
tion, and high frequency electric oscillations are attended with 
luminosity of pt te conductors, only one answer to this 
periments, undertaken in an attempted verification of the 
theoretical provisions of Maxwell. To these, therefore, a brief 
reference will be necessary 
Briefly stated Maxwell's theory amounted to this. The 
displacement. Now, if electromotive intensity is assumed to 
be proportional we electric displacement, the never 
energy of the field can be written down as a volum ral, 
in terms of élebteio Mplnsebdans. The elovtioiingnetic 
energy can, in the same way, be expressed as a volume 
integral, in terms of magnetic induction. Assuming further, 
that the former is potential energy and the latter kinetic, 
energy, by the application of a general dynamical principle, 
called the Principle of Least Action, the equations of motion 
of an electric disturbance can be obtained sce ‘ere are found 
to be meg it to transverse wave propagat 
well was thus led to conclude that ‘tlie electromag- 
netic field and the luminiferous medium are “identical.” His 
now being reviewed, in terms of the latest theories. 
“To fill all space,”’ said Maxwell, “ with a new medium, 
whenever any new phenomenon is to be explained is by no 
means philosophical; but if the study of the different 
branches has independently suggested the idea of a medium 
and, if the properties which must be attributed to the medium, 
ous medium, in order to account for the phenomenon of light, 
the evitieae for the physical existence of the medium will 
be considerably strengthened.” And this evidence appeared to 
direc 
rye ste eagag it will fee ‘dbtieable | for us to examine briefly, 
in d 
