FORGE 35 



" Qu. 22. May not Planets and Comets, and all 

 gross Bodies, perform their motions more freely, and 

 with less resistance in this Aetherial Medium than in 

 Fluid, which fills all Space adequately without leaving 

 any Pores, and by consequence is much denser than 

 quicksilver and gold? And may not its resistance be 

 so small as to be inconsiderable? For instance, if 

 this Aether (for so I call it,) should be supposed 

 700,000 times more elastic than our Air, and about 

 700,000 times more rare, its resistance would be above 

 600,000,000 times less than that of Water. And so 

 small a resistance would scarce make a sensible alter- 

 ation in the Motions of the Planets in ten thousand 

 years," etc.* 



I quote the above to show that Newton regarded a 

 medium as necessary in order to explain the action of 

 gravity. 



I may here remark that of all the forces of nature, 

 gravity is least understood as to its method of action. 

 No theory has been offered that meets the difficulties 

 involved. 



The belief in the existence of ether, a universal 

 medium, has grown out of facts connected with light. 

 It is now admitted by the scientific world, that light 

 consists of the vibrations of ether that can be recog- 

 nized by the eye. While the vibrations of matter 

 which produce audible sounds are limited to about 

 50,000 per second, the vibrations of ether which pro- 

 duce red light are 370 trillions, and violet light 739 

 trillions per second ; and beyond the violet are invis- 

 ible rays that vibrate at a still higher rate, while below 

 the red are rays of heat which have a slower rate of 

 vibration than the rays of light. 



In the solar spectrum, produced by the passage of 

 the sun's rays through a prism, we find heat, light 



♦Modern Views of Electricity, by Lodge, p. 406. 



