ETHER (ante). The ancients had a shadowy idea, or theory it may be called, in regard to the medium which we term cosmic, or luminiferous, ether. The ancient Greeks personified it, "Ether being, according to Hesiod, the son of Erebus and Night, and the brother of Day. They also regarded this personification as the representation of the great force of the universe, as well as original matter, which, in a mysterious union with this force, evolved the worlds. The Orphic hymns speak of "Ether as the soul of the world, the animator of all things, the great principle of life, the divine essence. The children of "Ether and Day were the objects of the visible creation, the heavens with all their stars, the land, the sea. "Ether was the lightest and the most active form of matter, and Day had the power of converting it into heavier and visible matter. It seems as though the human mind has the power, given it by the creator, of foretelling great truths afterwards to be demonstrated. Plato spoke of tether as being a form of matter far purer and lighter than air; so light that its weight cannot be ascertained because diffused through infinite space. It would at first appear surprising that the substance which Huyghens found it necessary to assume to demonstrate the laws of reflec tion and refraction, and particularly of double refraction, should not have been regarded by the greater portion of the scientific world as a reality, as a substance necessary for the performance of many physical phenomena. But Newton's emission theory of light, or, perhaps it may more correctly be said, his elaboration of the emission theory of Des cartes, held the belief of the world for nearly a century and a half, and this theory did not require the supposition of such a medium, although both Newton and Descartes conceived of its existence. Huyghens's undulatory theory was so thoroughly founded upon the doctrine of an ether that its opponents were perhaps, in their opposition to his theory, insensibly led to ignore the existence of this medium ; for the propagation of light by the emission of particles of matter needed no medium for them to pass through; they could pass through vacuous space, although there were some phenomena which seemed to suggest that the assumption of such a medium would aid in their explanation.
But Huygliens's theory required the existence of the medium, although, strange as it may seem, the great mathematician Euler, an advocate of the doctrine of undulations, rejected the doctrine of an ethereal medium. Prof. Grove, a modern British scientist, in his essay on the Correlation of Physical Forces, offers the following arguments, here briefly stated, against the doctrine of a cosmic ether. The tendency that the particles of bodies have to fly off into space is so great that it has been impossible hitherto to cause an inclosed space to be void of ponderable matter. Gaseous matter has so strong a tendency to fly off into space that no part of the universe could, after a time, be free from its particles. Again, it must be assumed that light is lost in the interstellar spaces, because, if it were not so, there could be no night, all of the stars being suns. Now. an argument which chimes in with the doctrine of the correlation of physical forces, is that the light from these innumerable suns is transmuted into another force, and this requires the existence of matter in the spaces, such matter as would be furnished by the expansion into space of the aerial matter which envelops the different worlds. The strongest arguments in favor of the belief in a cosmic ether are that it allows of a perfect explanation of all the phenomena of radiation, refraction, diffraction and polar ization of light, and that such explanation cannot be made without assuming the exis tence of such a medium. See Rant AND LIGIIT.