284 CLASSICS OF MODERN SCIENCE 

 the same time, the correctness of which remained 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 erroneous conclusions, his experiment was not quite 

 unsuccessful. He discovered a law which now bears his name, and 

 to which I will return further on. 



His labors remained for a long time without notice, and it was not 

 till eighteen years afterwards, that is, in 1842, that different investi- 

 gators 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 ex- 

 pressed it correctly, was a German physician, J. R. Mayer, of Heil- 

 bronn, in the year 1842. A little later, in 1843, ^ Dane, named Cold- 

 ing, 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, followed 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 

 view. My inquiry was made public in 1847, in a small pamphlet 

 bearing the title, "On the Conservation of Force." 



Since that time the interest of the scientific public for this subject 

 has gradually augmented. A great number of the essential conse- 

 quences of the above manner of viewing the subject, the proof of 

 which was wanting when the first theoretic notions were published, 

 have since been confirmed by experiment, particularly by those of 

 Joule ; and during the last year the most eminent physicist of France, 

 Regnault, has adopted the new mode regarding the question, and 

 by fresh investigations on the specific heat of gases has contributed 



