in the Theory of Gravitation. 451 



pothetical part of the theory with the adage in question that led 

 Sir Isaac Newton to suggest that gravity might be transmitted 

 by means of an sethereal medium existing in space. 



Another objection is this : if another particle C be placed be- 

 side B, it will be found that A will attract C with as much force 

 as it does B, and yet continue to attract B the same as though 

 C had not been added; and if we add another particle D, this 

 particle will also be attracted with equal force, the other two 

 remaining as strongly attracted by A as though D had never 

 appeared. We might in like manner go on adding particle to 

 particle to infinity, and still A would continue to attract each 

 new particle as it appeared with as much force as though no 

 other particle were in existence. In fact there is no limit to this 

 attracting power of A. This is contrary to what we know of the 

 character of force in every other department of nature. 



Another objection also follows ; when we add C to B and thus 

 double the attraction, A doubles its force also and attracts them 

 with as much force as they attract it. If D be added, the at- 

 traction is tripled, but A triples its force also ; and we might 

 proceed in this manner adding particle to particle until we had 

 added to B every particle in the universe, and yet, strange to 

 say, the single particle A would attract the entire universe with 

 as much force as the universe attracted it. 



The attraction theory is also in opposition to the principle of 

 the Conservation of Force, as has been shown, I think, clearly 

 by Faraday"*. When a stone, for example, is thrown upwards 

 from the earth, it not only loses all its motion, but it loses its 

 attraction in proportion to the square of its distance from the 

 centre of the earth. What becomes of the motion imparted to 

 the stone ? It is not transformed into attraction, for the attrac- 

 tion diminishes as well as the motion. When the stone again 

 falls to the earth, it gains both motion and attraction. In the 

 former case the attraction is said to consume the motion, and, 

 instead of becoming stronger, becomes weaker in consequence ; 

 and in the latter case it imparts this same motion, and yet, after 

 imparting the motion, it is actually found not only not to have 

 lost, but to have gained force thereby. Faraday justly asks what 

 becomes of the force or motion imparted to the stone ? It is 

 not converted into attraction, for the attraction becomes less in- 

 stead of greater in consequence. And in the case of the falling 

 stone, where does the motion come from ? If the motion arises 

 from the attraction of the earth, then there must be a certain 

 amount of this attractive force converted into motion; and if so, 

 the attractive force should be so far reduced ; but instead of this, 

 it is actually increased. There is, therefore, no account given 



* Phil. Mag. for April 1857. 



