; II HUMANS LUDWIO FERDINAND HELMHOLTZ. 



by experiment, calculation, or speculation, to the establishment of the principle 

 >f the conservation of energy; but there can be no doubt that a very great 

 impulse was communicated to this research by the publication in 1847, of 

 Hchuholu'a essay Ueber die Erhaltung der Kraft, which we must now (and 

 correctly, as a matter of science) translate Conservation of Energy, though in 

 the translation which appeared in Taylor's Scientific Memoirs, the word AV.;/'c 

 was translated Force in accordance with the ordinary literary usage of that 



time. 



In this essay Helmholtz shewed that if the forces acting between material 

 bodies were equivalent to attractions or repulsions between the particles of these 

 bodies, the intensity of which depends only on the distance, then the con- 

 figuration and motion of any material system would be subject to a certain 

 equation, which, when expressed in words, is the principle of the conservation 

 uf energy. 



Whether this equation applies to actual material systems is a matter which 

 experiment alone can decide, but the search for what was called the perpetual 

 motion has been carried on for so long, and always in vain, that we may now 

 appeal to the united experience of a large number of most ingenious men, any 

 one of whom, if he had once discovered a violation of the principle, would 

 have turned it to most profitable account. 



Besides this, if the principle were in any degree incorrect, the ordinary 

 processes of nature, carried on as they are incessantly and in all possible com- 

 binations, would be certain now and then to produce observable and even 

 startling phenomena, arising from the accumulated effects of any slight diver- 

 gence from the principle of conservation. 



But the scientific importance of the principle of the conservation of energy 

 does not depend merely on its accuracy as a statement of fact, nor even on 

 the remarkable conclusions which may be deduced from it, but on the fertility 

 of the methods founded on this principle. 



Whether our work is to form a science by the colligation of known facts, 

 or to seek for an explanation of obscure phenomena by devising a course of 

 experiments, the principle of the conservation of energy is our unfailing guide. 

 It gives us a scheme by which we may arrange the facts of any physical 

 science as instances of the transformation of energy from one form to another. 

 It also indicates that in the study of any new phenomenon our first inquiry 

 must be, How can this phenomenon be explained as a transformation of energy? 



