502 Mr. Exley's Remarks on M. Mossotti's Theory of Physics, 



Mr. Babbage, as above stated, has presented the theory in 

 a modified form, in which the repulsions are regulated by 

 some given law, and the attraction by some other given law. 

 First, let there be no central solids, and take two molecules 

 A and B, and let one of them, A, be plunged into the aether; 

 it will, as in the former case, attract the centres of aethereal 

 atoms into its centre, till just so many are concentrated as are 

 equal in force to the molecule at its centre: but since the law 

 of attraction is different from that of repulsion, the actions of 

 the compound atom, on any distant atom, will be different. 

 And now let the molecule B, with its concentrated aether, be 

 placed at a distance from A, and let the molecule A attract 

 the concentrated atoms of B with the force ft, and let the con- 

 centrated atoms of A repel the same with the force m ; there- 

 fore the attraction of the compound atom A on the concen- 

 trated atoms of B is n—m. Again, because of the equal forces 

 at the centre, we have the attraction of the concentrated atoms 

 of A on the molecule B equal to m ; and the repulsion of the 

 molecule A on that of B is n : therefore the attraction of the 

 compound atom A on the molecule B is m — n : consequently 

 the attraction of the compound atom A on the compound 

 atom B is n — m + m— w = 0, so that two distant atoms neither 

 attract nor repel. If very small solids be supposed to occupy 

 the centres, the same will follow; because whatever is the law 

 of force, the effect on atoms whose distance is great in com- 

 parison of the diameter of the body, will be the same as if 

 the atoms were collected in the centre of gravity of the 

 body (Math. Prin. of Mech. Phil.) ; hence the effect in this 

 case will be the same as before: therefore according to the 

 theory thus modified, whatever may be the given laws of force, 

 no action on distant atoms can result: the theory is therefore 

 erroneous. 



Having thus shown that Mossotti's theory is not the true 

 one, it may be added, that I have frequently tried my own by 

 such tests as occurred: it is possible that prejudice may have 

 had some influence in preventing me from discovering my 

 own errors, if such there be, in the principles. It would to me 

 be a kindness if some philosopher would undertake to prove 

 any defects which he may conceive militate against my 

 theory : if he show it to be inadequate he should have my sin- 

 cere thanks, however unexpected and unpleasant it might be 

 to my views and feelings, as it would save me much expendi- 

 ture of time and thought, of which, besides property, much 

 has been devoted to this subject, with a view to the interests 

 of philosophy, without other emolument : so that should the 

 theory be proved insufficient it would conduce to my advan- 



