Cliase.] '^'^" [Oct. 6, 



tion in Note 274, and opens a wide field for analytical rcsearcli respecting 

 the equilibrating tendencies between centripetal and centrifugal energy. 

 The stability' of major axes, in orbital revolution, is no more necessary 

 than the reciprocal equality of radiodynamic action and reaction in elastic 

 media. 



277. Relations of Earth to the Asteroids. 



Different portions of the asteroidal belt are so related to* Earth's varying 

 positions as to share the influence, either directly or through the conver- 

 sion of oscillatory ms vim into projectile vis viva, of linear, spherical and 

 explosive centres of oscillation. One of these relations, which seems 

 specialh" important and significant in connection with the m^iintenance 

 of solar energy, is found by dividing the virtual radius of solar torsion 

 (ar„ = 688.95r„) by Earth's mean radius vector {p^ =■ 214.45ro). This 

 gives a relative distance of 1 -r- 3.21^, and a relative orbital velocity 

 of (3.2134 — 1)2" = 1.7926 -r- 1 at the chief centre of condensation 

 in the solar system, as compared with the orbital velocity at the ex- 

 tremity of the radius of torsion. ' This is within about ^V of one 

 per cent, of the ratio (1.8) of the vis vioa of oscillating particles to 

 the vis viva of wave propagation, which was indicated by me in 1872 

 (Proc. Am. Phil. Soc, xii, 394), and by Maxwell in 1877 (Phil. Mag. 

 [5] iii., 453, iv. 209). A portion of this trifling difference may be ex- 

 plained by the gradual diminution of sethereal density upon receding 

 from stellar centres (iSTote 240). 



278. Qollateral Hypotheses. 



In investigating the relations of centripetal and centrifugal action and 

 reaction, it seems desirable to consider and compare the following hypo- 

 theses and conclusions : 



1. Laplace's estimate that the velocity of transmission, in gravitating 

 acceleration, is at least 100,000,000 times as great as that of light.- 



2. LeSage's hypothesis that gravitation and luminous undulation repre- 

 sent equal actions and reactions. 



3. Faraday's fruitless search for a gravitating constant which would 

 satisfy his interpretation of the doctrine of conservation of energy. 



4. Herschel's comparison of the mean vis viva of light, with that ot 

 sound. « 



5. Weber's identification of the velocity of light (v.), with the " electro- 

 magnetic ratio" (we). « 



G. Berthelot's "explosive waves," and their action upon sound waves. 



7. The inquiries of Siemens into the combined influence of rotation, cen - 

 trifugal action, gravitating force, and chemical affinity. 



8. The various attempts of Thomson, Rankine, Maxwell, Eddy, and 

 others, to escape the apparent consequences of the second law of thermo- 

 dynamics. 



