Chase.] ill. [Feb. 6,1874. 



OKIGIN OF ATTRACTIVE FORCE. 



By Prof. Pliny Eakle Chase. 



{Read before the American PhilosopJiical Society, February QtJi, 1874.) 



The theoretical cycles and epicycles of Ptolemy and his predecessors, 

 the vortices of Descartes, the sether of Newton, were all suggested by an 

 instinctive search for some simple primitive form or cause of motion. 



Gravitation is supposed to act under uniform laws in all parts of the 

 universe, and many attempts have been made to refer it to some form of 

 sethereal undulation. Its proportionality, directly to the mass and in- 

 versely to the square of the distance, maybe readily accounted for on 

 the hypothesis that it is the resultant of infinitesimal impulses, moving 

 with a uniform velocity. 



Prof. Stephen Alexander has supposed that the Star System, of which 

 our Sun is a member, is a spiral with several branches. The logarithmic 

 parabola between a Centauri and the Sun, which I have pointed 

 out as controlling the positions of the planets,* confirms this hypothesis, 

 and also furnishes evidence of a material, elastic, slightly compressible 

 Esther. 



In the spherical undulatious of such an aether, propagated like the 

 waves of light, the perimetral disturbance must be r times as great as 

 the synchronous diametral disturbance. 



Under the action of central forces, in consequence of the synchronism 

 in all orbits of the same major axis :— 



1. A body would describe a circular orbit in the same time that it would 

 oscillate through the centre, over a space equivalent to two diameters. 

 The velocity of the circular oscillation would therefore be ^ of the mean 

 velocity of the radial oscillation. 



2. A body would oscillate from a circumference to the centre and re- 



3 



turn, in {^)^ of the time of orbital revolution. 



3. A body would oscillate through a diameter and return in (|^)"-' of 

 the time of orbital revolution, or in the time which would be required 

 for revolution through the same orbit, with the velocity acquired by in - 

 finite impulsion to the circumference. 



4. If the velocity of orbital approach to a focus of central force is so 

 retarded, by collisions or otherwise, as to change the orbit from a para- 

 bola to a circle, the velocity of the circular oscillation will be ~ of the 

 mean velocity of the retarded radial oscillation. 



Let us suppose that the planetary groupings, as well as the velocities 

 of planetary revolution, solar and planetary rotation, and solar motion in 

 space, are all resultants of successive infinitesimal impulses, moving with 

 a uniform velocity, and propagated through the medium of a universal 

 aether. 



*Proc. A. P. S., Sept. 20, 1872. 



