ATOMIC THEORY OF THE ETHER 



ing polarity, the Ions of the molecule, but which 

 united in a molecule moves and acts as a unit. These 

 molecules are extremely small and move in all direc- 

 tions with enormous rapidity through free paths 

 exceeding even planetary distances in length ; they 

 are individually, absolutely elastic, are relatively 

 close together and move with such extreme swift- 

 ness that with their excessive minuteness they inter- 

 penetrate the interstices of all ponderable matter. 

 They are of infinite number and of uniform nature. 

 According to Newton's first law, that of Inertia, 

 their rapid translatory motion is self-inherent; that 

 is to say, not dependent upon any other pre-existent 

 motion for their continuance. According to his 

 second law, that of Motion, any change of motion 

 must be proportional to the force applied and in a 

 straight line in the direction of the altering force. 

 They thus form in free space a consistent isotropic 

 medium of extreme tenuity, but which, owing to the 

 enormous velocity of its molecules, possesses great 

 rigidity, since the moving corpuscles, having a 

 momentum equal to their individual mass multi- 

 plied by the square of their velocity, will require a 

 force as great as their own to deflect them at right 

 angles from their path and position. This velocity 

 must at least equal that of the supposed corpuscles 

 in the Kathodic rays, which J. J. Thompson estimates 

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