442 Models illustrating some Properties of the ther. 
course these mechanical details could hardly be carried out so 
as to work with sufficiently little friction for the working of 
any actual model to approximate sufficiently closely to that 
of the ether for it to be worth while attempting to construct 
it). The faces of the cube should be filled up with diaphragms 
past which the paddle-wheels should pump liquid, and whose 
elasticity should be the means of storing electrostatic energy 
in the medium. It may be worth while pointing out some 
of the results of having shown that the energy of a disturbance 
of this medium would be represented by the same equations 
as those Maxwell has shown to hold for the ether. The most 
complicated results follow from supposing the faces of the 
cubes, of which the medium is constructed, to have different 
elasticities. Such a structure represents a crystalline medium. 
Its vibrations would be propagated according to the laws of 
propagation of light in crystalline media. The wave-surface 
would be Fresnel’s wave-surface, and it would exhibit conical 
refraction. If the cubes were twisted, the structure would be 
like that of quartz or other substances that rotate the plane 
of polarization of light. In order to represent the rotation of | 
the plane of polarization of light by magnetism, it would be 
necessary to introduce some mechanism connecting this ether 
with matter. That this would be required is evident from 
the consideration that noamount of inherent rotation of these 
wheels would alter the plane of polarization of a vibration 
transmitted by them. Now, although I am not prepared to 
suggest any actual method of connection, it may be worth 
while pointing out two different ways in which it may work. 
In the first place the matter may be in rotation when subject 
to magnetic force ; and it may be connected with the ether in 
such a way that the direction of its axis and rotation is altered 
by the vibrations passing in the ether. It would then react 
on the ether in such a way as to rotate the plane of polariza- 
tion of the wave. In the second place the matter might only 
act asa link connecting ether elements rotating in rectangular 
directions in such a way that the rotation of one element 
altered the axis of rotation of a rectangular element. The 
reaction of this latter on the former would then rotate the 
plane of polarization of a wave propagated parallel to the 
latter. The first of these connections is that in accordance with 
Maxwell’s theory as to the connection between the ether and 
matter that he introduces in his ‘ Electricity and Magnetism,’ 
in order to explain the rotation of the plane of polarization of 
light by magnetism; while the second is the one that [ 
supposed in my paper “ On the Electromagnetic Theory of 
the Reflection and Refraction of Light” (RK. 8. Trans. 1880). 
