180 ANNUAL OF SCIENTIFIC DISCOVERY. 



though I have experimented* and as yet failed, I think experiment would be 

 well bestowed, I mean the force of gravitation. I believe I represent the 

 received idea of the gravitating force aright in saying that it is a simple at- 

 tractive 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, 

 including myself, who in that respect may be of like mind with him. t 



This idea of gravity appears to me to ignore entirely the principle of the 

 conservation of force; and by the terms of its definition, if taken in an ab- 

 solute sense, "varying inversely as the square of the distance," to be in 

 direct opposition to it, and it becomes my duty now to point out where this 

 contradiction occurs, and to use it in illustration of the principle of conserv- 

 ation. Assume two particles of matter, A and B, in free space, and a force 

 in each or in both by which they gravitate towards each other, the force 

 being unalterable for an unchanging distance, but varying inversely as the 

 square of the distance when the latter varies. Then, at the distance of ten, 

 the force may be estimated as one ; whilst at the distance of one, that is, one 

 tenth of the former, the force will be one hundred ; and if we suppose an 

 elastic spring to be introduced between the two as a measure of the attrac- 

 tive force, the power compressing it will be a hundred times as much in the 

 latter case as in the former. But from whence can this enormous increase 

 of power come? If we say that it is the character of this force, and content 

 ourselves with that as a sufficient answer, then it appears to me we admit a 

 creation of power and that to an enormous amount ; yet by a change of con- 

 dition, so small and simple as to fail in leading the least instructed mind to 

 think that it can be a sufficient cause, we should admit a result which would 

 equal the highest act our minds can appreciate of the working of infinite 

 power upon matter ; we should let loose the highest law in physical science 

 which our faculties permit us to perceive, namely* the conservation of force. 

 Suppose the two particles, A and B, removed back to the greater distance 

 often, then the force of attraction would be only a hundredth part of that 

 they previously possessed ; this, according to the statement that the force 

 varies inversely as the square of the distance would double the strangeness 

 of the above results; it would be an annihilation of force an effect equal in 

 its infinity and its consequences with creation, and only within the power of 

 Him who has created. 



We have a right to view gravitation under every form that either its defi- 

 nition or its effects can suggest to the mind ; it is our privilege to do so with 

 every force in nature ; and it is only by so doing that we have succeeded, to 

 a large extent, in relating the various forms of power, so as to derive one 

 from another, and thereby obtain confirmatory evidence of the great principle 

 of the conservation of force. Then let us consider the two particles, A and 

 B, as attracting each other by the force of gravitation, under another view. 

 According to the definition, the force depends upon both particles, and if the 



* Philosophical Transactions, 1851, p. 1. t See second note on pnge 183. 



