OX THE INTERACTION OF NATURAL FORCES. 167 



be easily and completely stated. It was found that all 

 known relations of forces harmonise with the consequences 

 of that assumption, and a series of unknown relations were 

 discovered at the same time, the correctness of which re- 

 mained to be proved. If a single one of them could be 

 proved false, then a perpetual motion would be possible. 



The first who endeavoured to travel this way was a 

 Frenchman named Carnot. in the year 1824. In spite of 

 a too limited conception of his subject, and an incorrect 

 view as to the nature of heat, which led him to some er- 

 roneous conclusions, his experiment was not quite unsuc- 

 cessful. He discovered a law which now bears his name, 

 and to which I will return further on. 



His labours remained for a long time without notice, 

 and it was not till eighteen years afterwards, that is in 



1842, that different investigators in different countries, 

 and independent of Carnot, laid hold of the same thought. 

 The first who saw truly the general law here referred to, 

 and expressed it correctly, was a Grerman physician, J. R. 

 Mayer of Heilbronn, in the year 1842. A little later, in 



1843, a Dane named Colding presented a memoir to the 

 Academy of Copenhagen, in which the same law found 

 utterance, and some experiments were described for its 

 further corroboration. In England, Joule began about 

 the same time to make experiments having reference to 

 the same subject. We often find, in the case of questions 

 to the solution of which the development of science 

 points, that several heads, quite independent of each 

 other, generate exactly the same series of reflections. 



I myself, without being acquainted with either Mayer 

 or Colding, and having first made the acquaintance of 

 Joule's experiments at the end of my investigation, fol- 

 lowed the same path. I endeavoured to ascertain all the 

 relations between the different natural processes, which 

 followed from our regarding them from the above point of 



