1857.] on the Cofiservation of Force, 357 



particle B at the distance of a mile with a certain degree of force ; 

 it will attract a particle C at the same distance of a mile with a 

 power equal to that by which it attracts B ; if myriads of like 

 particles be placed at the given distance of a mile, A will attract 

 each with equal force ; and if other particles be accumulated round 

 it, within and without the sphere of two miles diameter, it will 

 attract them all with a force varying inversely with the square of 

 the distance. How are we to conceive of this force growing up in 

 A to a million fold or more ? and if the surrounding particles be 

 then removed, of its diminution in an equal degree ? Or, how are 

 we to look upon the power raised up in all these outer particles by 

 the action of A on them, or by their action one on another, without 

 admitting, according to the limited definition of gravitation, the 

 facile generation and annihilation of force ? 



The assumption which we make for the time with regard to the 

 nature of a power (as gravity, heat, &c.), and the form of words in 

 which we express it, i.e, its definition, should be consistent with the 

 fundamental principles of force generally. The conservation of 

 force is a fundamental principle ; henc'e the assumption with regard 

 to a particular form of force, ought to imply what becomes of the 

 force when its action is increased or diminished, or its direction 

 changed ; or else the assumption should admit that it is deficient on 

 that point, being only half competent to represent the force ; and, 

 in any case, should not be opposed to the principle of conservation. 

 The usual definition of gravity as an attractive force between the 

 particles of matter varying inversely as the square of the distance, 

 whilst it stands as a full definition of the power, is inconsistent 

 with the principle of the conservation of force. If we accept the 

 principle, such a definition must be an imperfect account of the 

 whole of the force, and is probably only a description of one exer- 

 cise of that power, whatever the nature of the force itself may be. 

 If the definition be accepted as tacitly including the conservation 

 of force, then it ought to admit, that consequences must occur 

 during the suspended or diminished degree of its power as gravita- 

 tion, equal in importance to the power suspended or hidden ; being 

 in fact equivalent to that diminution. It ought also to admit, that 

 it is incompetent to suggest or deal with any of the consequences of 

 that changed part or condition of the force, and cannot tell whether 

 they depend on, or are related to, conditions external or internal to 

 the gravitating particle ; and, as it appears to me, can say neither 

 yes nor no to any of the arguments or probabilities belonging to 

 the subject. 



If the definition denies the occurrence of such contingent results, 

 it seems to me to be unphilosophical ; if it simply ignores them, I 

 think it is imperfect and insufficient ; if it admits these things, or 

 any part of them, then it prepares the natural philosopher to look 

 for effects and conditions as yet unknown, and is open to any degree 

 of development of the consequences and relations of power : by 



