THE 

 LOiNDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



MAY 1873. 



XLI. On the Ultramundane Corpuscules of Le Sage, also on the 

 Motion of Rigid Solids in a Liquid circulating irrotationally 

 through perforations in them or in a Fixed Solid. By Sir 

 William Thomson, F.R.S* 



LE SAGE, bora at Geneva in 1724, devoted the last sixty-three 

 years of a life of eighty to the investigation of a mechanical 

 theory of gravitation. The probable existence of a gravific me- 

 chanism is admitted, and the importance of the object to which 

 Le Sage devoted his life pointed out, by Newton and Rumfordf 

 in the following statements : — 



"It is inconceivable that inanimate brute matter should, without 

 the mediation of something else, which is not material, operate 

 upon, and affect other matter without mutual contact ; as it must 

 do, if gravitation, in the sense of Epicurus, be essential and in- 

 herent in it. And this is the reason why I desired you would 



* Communicated by the Author, from the Proceedings of the Royal 

 Society of Edinburgh, 1871-72. 



t On the other hand, by the middle of last century the mathematical 

 naturalists of the Continent, after half a century of resistance to the New- 

 tonian principles (which, both by them and by the English followers of 

 Newton, were commonly supposed to mean the recognition of gravity as a 

 force acting simply at a distance without mediation of intervening matter), 

 had begun to become more " Newtonian " than Newton himself. On the 

 4th February, 1744, Daniel Bernoulli wrote as follows to Euler : f( Uebri- 

 gens glaube ich, dass der Aether sowohl gravis versus solem, als die Luft 

 •versus terrain sey, undkann Ihnen nicht bergen, dass ich liber diese Puncte 

 ein volliger Newtonianer bin, und verwundere ich mich, dass Sic den Prin- 

 cipiis Cartesianis so lang adhariren ; es mochte wohl einige Passion vielleicht 

 mit unterlaufen. Hat Gott konnen eine animam, deren Natur uns unbe- 

 greiflich ist, erschaffen, so hat er audi konnen eine attractionem uuiver- 

 salem materise imprimiren, wenn gleich solche attractio supra caption ist, 

 da hingegen die PrincipiaCartesiana allzeit contra caption etwas involviren." 



Phil. Mag. S. 4. Vol. 45. No. 301. May 1873. Y 



