KINETICS OF THE ETHER. 



To return to the hypothesis of the Atomic theory 

 of the Ether as explaining thereby the cause of gravi- 

 tation. 



The atoms of the Ether are supposed to be, as 

 before described, moving through all space equally 

 swiftly and in all directions. A mass of matter is 

 known to be a congeries of molecules, in which the 

 spaces between the contiguous molecules, considered 

 as spheres, are far greater than the space actually 

 occupied by the molecule. This ratio between the 

 vacuous interval and the solid molecule becomes 

 greater in proportion as the size of the molecule is 

 diminished. (The vortex theory of Lord Kelvin, if 

 tenable, would, of course, enormously increase the 

 vacuous spaces.) " Tait assumes that it is probable 

 that the molecule itself does not occupy as much as 

 five per cent, of the whole space." The Ether pene- 

 trates into or occupies the space between the mo- 

 lecules of all bodies, through which it passes owing 

 to the extreme relative as well as the absolute small- 

 ness of its atoms, as air would pass through the in- 

 terstices of a fishing net or of a sponge. The aggre- 

 gate molecules of a body isolated in the Ether of 

 interstellar space would be subjected to the concus- 

 sions of the ethereal atoms moving from all directions 

 with almost inconceivable swiftness, and with an 

 energy proportionate to the square of the velocity of 



