1864.] 357 [Chase. 



magnetic influence, that can be explained only by the conversion of 

 gi'avity into magnetism or the reverse. 



Prof. Faraday, in a lecture before the Royal Institution in the 

 year 1857, endeavored to show that our usual conception of gravity 

 is not in harmony with the principle of '' conservation of force." 

 Prof. Brticke* and others, have tried to remove the difficulties in 

 which the question is involved, but I believe none of the proposed 

 solutions have been satisfactory to the learned philosopher who first 

 started the discussion. 



It has even been questioned whether gravity can be properly 

 called a force, or whether it is anything more than a simple '' ten- 

 dency." Prof. Brticke has shown conclusively, that it is subject, 

 like heat and other recognized forces, to all the laws which regulate 

 the interchange of actual and potential energy; and our barometrical 

 investigations furnish a beautiful illustration of the manner in which 

 its tension is balanced by opposing forces. 



We speak, indeed, of weight, as if it could be predicated only of 

 bodies at rest, and as if it were so entirely distinct from momentum 

 that no comparison could be properly instituted between the two. 

 Precisely the reverse is true. Absolute rest is apparently an impos- 

 sible condition of matter, for, to whatever extent the action of op- 

 posing forces may be relatively neutralized, the inconceivable rapidity 

 of aDthereal, planetary, and stellar motions, produces a constant change 

 of place. Even if we confine our attention to the earth alone, in 

 each instant (dt), every particle has a tangential motion (tan. d^), 

 and a central motion of gravity (sin. d'^^) that constitutes a vis viva 

 which we call its weight, and which is in equilibrium with the elas- 

 ticity of the molecular aether. The sum of all the instantaneous 

 energies is the same, whether the particle fall freely for any given 

 time, or remain apparently at rest. All the potential energy which 

 is transformed in one case into the actual energy of motion,! in the 



* Phil. Mag., 4 S., 15, 81. 



t The potential energy of gravity is represented by §• ^ 32 ft. per second. The 

 earth's rotation allowing only about ^1^ of this amount, or .1107 ft. per second, to 

 be converted into actual energy, the remainder must be employed in overcoming 

 molecular elasticity. The formula a = ( — — )i gives 26,221 miles as the 



V 4;r ^ / 



radius of the sphere of attraction that is in equilibrium with the molecular elas- 

 ticity at the earth's surface. These opposing forces must produce constant oscil- 

 lations, and by the study of these oscillations, it may perhaps be possible to recon- 

 cile the several hypotheses of Newton, Faraday, Mossotti, and Challis, respecting 

 the nature of gravitation. See Phil. Mag., 4 S., v. 13, p. 231-7, and v. IS, p. 447, 

 sqq. 



