This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: … CHAPTER XIV THE PARTICLE OF THE ELECTRIC CURRENT TYNDALL’S treatise on the relations of heat to motion marked an epoch in physical science: we are now entering upon greatly enlarged views of motion. In the consideration of the theory of the electric nature of energy–the electromagnetic theory–we conceive of a universal ether by means of which the electrodynamic waves travel through space. This medium is supposed by some to be continuous, by others to have a grained structure. It is certainly easier to conceive of a grained structure than of continuous matter: water seems to be a type of continuity, but we know that it is made up of molecules or atoms of hydrogen and oxygen. Water is incompressible, the ether of space is also supposed to be incompressible. Waves of water travel just as the waves of energy traverse space: a cork on water moves up and down at right angles to the direction of propagation of a wave, the undulations of the electrodynamic waves in the ether are also at right angles to the direction of the waves. Some think in regarding the movement of waves in water that the ether may be composed of infinitely small particles which constitute an ocean. The fluid theories of electricity which prevailed in Franklin’s time had the same idea of continuity that the present theory of ether has. We have freed ourselves from a belief in fluid theories and seem to advance to a theory of grained structure of the ether. We shall see in considering the new subject of photo-electricity the effeet of ultra-violet light upon electrical charges that grave doubts are rising in regard to the continuous nature of the ether. The electromagnetic waves are revealed in the release of chemical bonds and in the phenomena of photo-electricity. When an…