Principle of the Conservation of Energy. 57 



Philosophical Magazine from other journals, and especially from 

 PoggendorfFs Annalen der Physik und Chemie. Since, however, 

 many beautiful investigations constantly appeared in the Philo- 

 sophical Magazine, I was at last induced to become myself a sub- 

 scriber to your celebrated Journal, and a few weeks ago I received 

 the Numbers that have been printed from the beginning of this 

 year till the first of October. 



On looking over the contents I found several papers and 

 memoirs of great interest to me ; but those of course are most 

 particularly interesting which treat of the new principle in rela- 

 tion to the forces of nature, which in Danish is called " The prin- 

 ciple of the imperishableness or perpetuity of Energy (Principet 

 for Krafternes Uforgcenyelighed), the most important part of 

 which is the Mechanical Theory of Heat ; and the questions con- 

 nected therewith that have lately been taken into consideration 

 in your Journal, and especially the historic notice of the mecha- 

 nical theory of heat by M. Verdet, in No. 170 of the Philoso- 

 phical Magazine (S. 4. vol. xxv. p. 467), induce me to send you 

 the following remarks, and to ask you to decide upon a question I 

 shall afterwards have the honour of laying before you, the favour- 

 able decision of which will give me very great pleasure. 



From the contents of the Numbers of the Philosophical Ma- 

 gazine which I have received (4th series, Nos. 165 to 175), I may 

 suppose that you are aware that M. Verdet and M. Helmholtz 

 think it right, according to what is known to them of my inves- 

 tigations, to place me next to M. Mayer in relation to the dis- 

 covery of the new principle touching the forces of nature ; but 

 at the same time I learn that many of the readers of your cele- 

 brated Journal have only a slight notion of my investigations and 

 memoirs on this subject, and that it may be presumed that most 

 of them have scarcely any idea at all about them. 



I regret very much that the Danish language is so little un- 

 derstood beyond the Scandinavian countries, as I learn from 

 M. Verdet' s historic notice is the case, although our Royal Society 

 of Science regularly exchange their Transactions, in which my 

 memoirs are printed, with most of the celebrated foreign societies; 

 but as I think it would perhaps interest your readers to see what 

 I have done, how I have done it, and at what time, and as it is 

 of course a matter of importance to me to be understood, and to 

 be placed in that position in relation to this discovery to which 

 I have a claim, I hope you will allow me to give here a short 

 outline of my investigations touching the new and important 

 principle of energy. 



The first idea I conceived on the relationship between the 

 forces of nature was the following. 



As the forces of nature are something spiritual and immaterial, 



