eed across the intervening space. As swift-footed messengers
they come, the bearers of life and beauty to distant planets. They come
to this our island home in space, these aetherial light waves, like rich
argosies freighted with the treasures of light, of life, of beauty, and
of glory, and the transmission of this life and beauty is effected by
the incessant wave motion generated in the Aether by the central body of
our solar system, the sun. Let us therefore endeavour to form a mental
picture of this aetherial wave motion with its transverse vibrations.

ART. 71. _Transverse Vibration of Light._--In the previous article we
saw that the vibration of light was transverse to the line of
propagation. If we could see the particles of air which are vibrating
when sound waves are produced, we should find that each particle or atom
is vibrating backwards and forwards in the direction of propagation.

In the case of an aetherial atom, however, which, according to our own
theory, participates in the vibration, we have to try to conceive of
each atom as vibrating across the line of propagation. So that if _A_
_B_ represents a ray of light proceeding from a luminous body, as the
sun (Fig. 5), then the vibration must be across the line, as up and down
and across that line as shown in the figure, each phase of the vibration
being at right angles to the line of propagation--that is, to _A_ _B_.
How can we form a physical conception of this phenomenon? There must be
some physical explanation to it, for if it be an effect there must be a
cause for its existence and production. Up to the present, however, no
physical explanation has been forthcoming, so that for over 200 years a
frictionless medium has failed to account for, or to explain, the
transverse vibration of light as suggested by Fresnel.

If, therefore, by the hypothesis of an atomic and gravitative Aether, we
succeed in accomplishing a result that a frictionless Aether has failed
to accomplish, then the explanation will be a most important factor in
proving the atomicity and consequent gravitative property of the Aether.

Let us therefore revert to our hypothesis of the Aether as given in Art.
45. From that we learn, because Aether is atomic, it is also
gravitative, and therefore forms around every atom and molecule, every
satellite, planet, sun and star, an aetherial atmosphere--such aetherial
atmosphere being doubtless proportionate to the mass of the atom or
molecule