Aether and Gravitation

by William George Hooper

The explanation may, or may not, be fully complete, but even if it be not perfectly correct, I am convinced that it will ultimately lead to a satisfactory physical explanation of this part of Maxwell's Theory of Light. In forming a conception as to the physical character of the vibrations in the electro-magnetic theory, we have to remember that there are three distinct vibrations, or motions, concerned in this theory.

1st. There is the direction of propagation.

2nd. There is the direction of the electric vibration which is at right angles to the direction of propagation.

3rd. There is the direction of the magnetic vibration or motion which is at right angles to both of the other two.

Now we have seen that the direction of propagation of any aetherial light ray, is that of a straight line from the sun corresponding to the radius vector ([Art. 76]). We have also seen that the front of a light wave is really that of a spherical shell ([Art. 71]).

We have also learned that the electric and the magnetic vibrations are in the wave front, so that these two vibrations, which are at right angles to each other, are to be found on the surface, so to speak, of each aetherial spherical shell, that surrounds the sun with ever-decreasing density, and ever-decreasing elasticity.

Let us try to picture the actual fact by an illustration. Let S be the sun, with concentric spherical aetherial shells surrounding it (Fig. 22). Then S A and S C will be rays of light being radiated out from the sun, and the magnetic and electric vibrations have to be both at right angles to the line of propagation and in the wave front; the wave front being represented by the circular lines showing the section of the concentric shells running north and south.

Now how can we picture these two motions at right angles to each other, and yet both at right angles to the line of propagation? First, let us take three straight lines and see how this may be done (Fig. 23).

Let A B, A S be two straight lines at right angles to each other, and A C another straight line at right angles to both. This can only be done by making A C perpendicular to the plane of the paper, and can be illustrated by supposing that it represents a pencil or pen placed upright on the paper, the point of the pencil being at point A. If this be done, then not only will A B and A C be at right angles to each other, but both will be at right angles to A S, which corresponds to the line of propagation.