446 On the Conservation of Force. [1857. 



of new laws or a new condition of force. The deficiency should 

 never be accepted as satisfactory, but be remembered and used 

 as a stimulant to further inquiry ; for conversions of force may 

 here be hoped for. Suppositions may be accepted for the time, 

 provided they are not in contradiction with the principle. Even 

 an increased or diminished capacity is better than nothing at 

 all ; because such a supposition, if made, must be consistent 

 with the nature of the original hypothesis, and may therefore, 

 by the application of experiment, be converted into a further 

 test of probable truth. The case of a force simply removed or 

 suspended, without a transferred exertion in some other direc- 

 tion, appears to me to be absolutely impossible. 



If the principle be accepted as true, we have a right to pursue 

 it to its consequences, no matter what they may be. It is, 

 indeed, a duty to do so. A theory may be perfection as far 

 as it goes, but a consideration going beyond it, is not for that 

 reason to be shut out. We might as well accept our limited 

 horizon as the limits of the world. No magnitude, either of 

 the phenomena or of the results to be dealt with, should stop 

 our exertions to ascertain, by the use of the principle, that 

 something remains to be discovered, and to trace in what di- 

 rection that discovery may lie. 



I will endeavour to illustrate some of the points which have 

 been urged, by reference, in the first instance, to a case of 

 power which has long had great attractions for me, because 

 of its extreme simplicity, its promising nature, its universal 

 presence, and its invariability under like circumstances ; on 

 which, though I have experimented* and as yet failed, I think 

 experiment would be well bestowed : I mean the force of gra- 

 vitation. I believe I represent the received idea of the gravi- 

 tating force aright, in saying, that it is 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. The usual idea of the force 

 implies direct action at a distance ; and such a view appears 

 to present little difficulty except to Newton, and a few, inclu- 

 ding myself, who in that respect may be of like mind with himf. 



This idea of gravity appears to me to ignore entirely the 

 principle of the conservation of force ; and by the terms of its 

 * Philosophical Transactions, 1851, p. 1. * See note, p. 451. 



