[ 597 ] 



LXEII. On a new Binary Progression of the Planetary 

 Distances, and on the Mutability of the Solar System. By 

 Henry Wilde, D.Sc, D.C.L., F'.R.S* 



1. TN the paper which I read before the Society in March 

 X. last " On the Moving Force o£ Terrestrial and 

 Celestial Bodies in relation to the Attraction of Gravita- 

 tion " f, it was demonstrated that the moving force of 

 celestial bodies is as the square of the velocity, in accordance 

 with the experimental results obtained with moving bodies at 

 the surface of the terrestrial globe. I further announced 

 and demonstrated the new dynamical law that the moving 

 force of celestial bodies is inversely proportional to the 

 square of the distance, and correlatively equal to the static 

 attraction of gravitation. For if the moving force were 

 simply as the velocity, the attraction of gravitation would 

 require to be in the like proportion, otherwise planetary 

 bodies would either fall upon the central body, or be projected 

 into outer space. But it has been demonstrated that the 

 moving force and the attraction of gravitation are alike in- 

 versely proportional to the square of the distance to maintain 

 and retain celestial bodies in their orbits during their revolu- 

 tions round their primaries. 



2. As some confusion of thought has arisen in the use of 

 the term " gravitating force " by various writers, it cannot be 

 too clearly stated that moving force and the static attraction 

 of gravitation, although strictly correlated, are as distinct 

 properties of body as dynamic electricity is from the static 

 force of magnetism, as each of these forces manifests itself 

 and may be treated upon independently of the others. 



3. As the moving and attractive forces of planetary bodies 

 are correlatively equal, and are expressed by the same 

 numbers, the radius vector of Mercury appeared to me the 

 most natural, as well as the most convenient unit to which 

 the other planetary distances should be referred. A further 

 reason for this selection was the fact that the terrestrial unit 

 is an obvious survival of the geocentric system of the universe 

 which has dominated science for ages, and still retains its 

 hold on ultra-anthropocentric writers on astronomy and 

 astrophysics. 



4. An apparently adverse feature, however, of the change 

 of unit in the new table, was the excision of the binary 



* Communicated by the Author. Head at a Meeting of the Man- 

 chester Literary and Philosophical Society, October 5th, 1909. 



+ Manchester Memoirs, vol. liii. (1909) ; Phil. Mag. (6) vol. xviii. 

 p. 523, 1909. 



