PHYSICAL SCIENCE. 11 



and limits to its action are not merely conversions or transla- 

 tions of power, testified in other forms and effects of material 

 change ? Most persons, justified by outward appearances, 

 would answer at once that a force has ceased to exist, when 

 the motions or other effects it induces on matter are no longer 

 present. The question, however, is one which rises far above 

 the mere evidence of the senses. Vaguely suggested at former 

 periods, it has been adopted in a definite shape by the philo- 

 sophers of our own time ; forced upon them, we may say, by 

 the course and character of recent discovery. It is the ques- 

 tion which forms the main topic of Mr. Faraday's lecture, 

 which lies before us, on the 6 Conservation of Force ; ' and 

 we willingly quote a few lines, both from the intrinsic weight 

 of all that comes from this source and as expressing what we 

 consider to be the growing conviction of all who have grappled 

 with this great problem of modern science. 



To admit that force may be destructible or can altogether dis- 

 appear, would be to admit that matter could be uncreated, for we 

 know matter only by its forces. Agreeing with those who admit 

 the conservation of force to be a principle in physics as large and 

 sure as that of the indestructibility of matter, or the invariability of 

 gravity, I think that no particular idea of force has a right to 

 unlimited or unqualified acceptance, that does not include assent to 

 it. ... Therefore I urge, that the conservation of force ought to be 

 admitted as a physical principle in all our hypotheses, whether 

 partial or general, regarding the actions of matter. 



This question, as we have said, was forced upon the 

 attention of men of science by the very nature of their recent 

 researches, and especially by the doctrine based upon them, 

 which is now developing itself under the title of the ( Co- 

 relation of Physical Forces ; ' a description modest as well as 

 apposite of a theory, which if matured, as we think it certain 

 to be, into full truth, will give new foundation and guidance 

 to the whole course of physical enquiry. In the work of Mr. 

 Grove, bearing this title, and prefixed to our article, we have 



