flames ever burning, robing the solar disc with its quivering fringe, or madly leaping on every side to a distance of one hundred thousand miles, and by their madness lashing the aetherial atmosphere into fury, creating aetherial waves, myriads upon myriads, and sending them with lightning speed 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 or planet as the case may be, in accordance with the Law of Gravitation. We shall consider this view of the subject later on. [Illustration: Fig: 5.]