THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENGP:. 



[FOURTH SERIES.] 



FEBRUARY 1858. 



XII. On Gravitation and the Conservation of Force. By Eknst 

 Brucke, Member of the Academy of Vienna, and Professor of 

 Physiology in the University*. 



ON the 27tli of February of the present year (1857) Faraday 

 gave a lecture in the Royal Institution f, i'l which he 

 sought to prove that our usual conception of the iorce of gravity 

 is not in harmony with the principle of the conservation of 

 force. In accordance with this conception, he defined gravity 

 as " a simple attractive force exerted between any two or all the 

 particles or masses of matter, at every sensible distance, but with 

 a strength varying inversely as the square of the distance." He 

 draws attention to the circamstance that this definition presup- 

 poses an actio in distans, a point which Newton himself found a 

 source of difficulty, and on which, in his third letter to Bentley, 

 he expresses himself in the following manner : — 



" That gravity should be innate, inherent and essential to mat- 

 ter, so that one body may act upon another at a distance, through 

 a vacuum, without the mediation of anything else, by and through 

 which their action and force may be conveyed from one to the 

 other, is to me so great an absurdity that I believe no man who 

 has in philosophical matters a competent faculty of thinking can 

 ever fall into it. Gravity must be caused by an agent acting con- 

 stantly according to certain laws; but whether this agent be mate- 

 rial or immaterial I have left to the consideration of my readers." 



Faraday shows, further, that as two particles are separated 

 from each other, their mutual attraction diminishes. This means 

 nothing else than that force is destroyed. Wlien two particles 

 arc brouglit more closely together, their mutual attraction aug- 



♦ From the Sitzunfjs-Berichte der Mathem. Natur. IViss. Classefdr 1857. 



t Our coiitiiifiital brcUircu oftea coufound the Royal Society and tlie 

 Royal Institution. — Ed. 

 Phil. Mag. S. 4. Vol. 15. No. 98. Feb. 1858. Q 



