The most interesting and important portion of physics at the present day is that constantly growing portion which is concerned with the properties and function of the universal connecting medium, the ether. All the phenomena of light, of electricity, and of magnetism, as well as of what is spoken of as radiant heat, are intimately connected with, and indeed Wholly dependent on, that medium; it is through these agencies that We have gradually become aware of its existence and able in some degree to Investigate it. Probably gravitation, cohesion, and chemical affinity are no less Closely associated with the ether; and it is becoming doubtful Whether matter itself could exist without it.
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