waves.

In the first of these cases the medium communicating the ripple or
wavelet is the water. In the second case the medium which sustains the
tremor and communicates the vibrations is the air.

Let us now take the case of a third medium, the substance of which
puzzled the philosophers of ancient time and still continues to puzzle
the scientists of the present. This is the ether, that attenuated fluid
which fills all inter-stellar space and all space in masses and between
molecules and atoms not otherwise occupied by gross matter. When a
lamp is lit the light radiates from it in all directions in a wave
motion. That which transmits the light, the medium, is ether. By this
means energy is conveyed from the sun to the earth, and scientists
have calculated the speed of the ether vibrations called light at
186,400 miles per second. Thus a beam of light can travel from the sun
to the earth, a distance of between 92,000,000 and 95,000,000 miles
(according to season), in a little over eight minutes.

The fire messages sent by the ancients from hill to hill were ether
vibrations. The greater the fires, the greater were the vibrations and
consequently they carried farther to the receiver, which was the eye.
If a signal is to be sent a great distance by light the source of that
light must be correspondingly powerful in order to disturb the ether
sufficiently. The same principle holds good in wireless telegraphy.
If we wish to communicate to a great distance the ether must be
disturbed in proportion to the distance. The vibrations that produce
light are not sufficient in intensity to affect the ether in such a
way that signals can be carried to a distance. Other disturbances,
however, can be made in the ether, stronger than those which create