458 On the Conservation of Force. [1857. 



of these results, if we left any of the others unregarded! That 

 there should be a power of gravitation existing by itself, having 

 no relation to the other natural powers, and no respect to the 

 law of the conservation of force, is as little likely as that there 

 should be a principle of levity as well as of gravity. Gravity 

 may be only the residual part of the other forces of nature, as 

 Mossotti has tried to show ; but that it should fall out from 

 the law of all other force, and should be outside the reach 

 either of further'experiment or philosophical conclusions, is not 

 probable. So we must strive to learn more of this outstanding 

 power, and endeavour to avoid any definition of it which is in- 

 compatible with the principles of force generally, for all the 

 phenomena of nature lead us to believe that the great and 

 governing law is one. I would much rather incline to believe 

 that bodies affecting each other by gravitation act by lines of 

 force of definite amount (somewhat in the manner of magnetic 

 or electric induction, though without polarity), or by an ether 

 pervading all parts of space, than admit that the conservation 

 of force could be dispensed with. 



It may be supposed, that one who has little or no mathe- 

 matical knowledge should hardly assume a right to judge of 

 the generality and force of a principle such as that which forms 

 the subject of these remarks. My apology is this : I do not 

 perceive that a mathematical mind, simply as such, has any 

 advantage over an equally acute mind not mathematical, in 

 perceiving the nature and power of a natural principle of action. 

 It cannot of itself introduce the knowledge of any new principle. 

 Dealing with any and every amount of static electricity, the 

 mathematical mind can, and has balanced and adjusted them 

 with wonderful advantage, and has foretold results which the 

 experimentalist can do no more than verify. But it could not 

 discover dynamic electricity, nor electro-magnetism, nor mag- 

 neto-electricity, or even suggest them ; though when once dis- 

 covered by the experimentalist, it can take them up with ex- 

 treme facility. So in respect of the force of gravitation, it has 

 calculated the results of the power in such a wonderful manner 

 as to trace the known planets through their courses and per- 

 turbations, and in so doing has discovered a planet before un- 

 known; but there may be results of the gravitating force of 

 other kinds than attraction inversely as the square of the di*- 



