126 ANNUAL OF SCIENTIFIC DISCOVERY. 



assumption, and a series of unknoAvn relations were discovered at 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 endeavored to travel this way was a Frenchman, named 

 Carnot, iu the year 1824. In spite of a too limited conception of his sub- 

 ject, and an incorrect view as to the nature of heat, which led him to some 

 erroneous conclusions, his experiment was not quite unsuccessful. He dis- 

 covered a law which now bears his name, and to which I will return fur- 

 ther on. 



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

 eighteen years afterwards, that is, in 1842, that different investigators in dif- 

 ferent 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 German physician, J. R. Mayer, of Heilbronn, in the year 

 1842. A little later, in 1843, a 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 indepen- 

 dent 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 endeavored to ascertain all the re- 

 lations between the different natural processes, which followed from our re- 

 garding 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 consequences 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 



* The following extract is taken from a lecture by Mr. Grove, delivered at the 

 London Institution, on the 19th of January, 18-12 : 



" Light, heat, electricity, magnetism, motion, and chemical affinity, are all con- 

 vertible material affections; assuming any one as a cause, one of the others will be 

 the effect. Thus heat may be said to produce electricity, electricity to produce 

 heat; magnetism to produce electricity, electricity magnetism; and so of the rest. 

 Cause and effect, therefore, in their relation to such forces, are words solely of con- 

 venience; we are totally unacquainted with the generating power of each and all 

 of them, and probably shall ever remain co ; we can only ascertain the normal of 

 their action ; we must humbly refer their causation to one omnipresent influer.ee, and 

 content ourselves with studying their effects, and developing by experiment their 

 mutual relations." 



" I have long held an opinion," says Mr. Faraday, in 1845, " almost amounting to 

 conviction, in common I believe with many other lovers of natural knowledge, 

 that the various forms under which the forces of matter arc made manifest have a 

 common origin, or in other words, are so directly related and mutually dependent, 

 that they are convertible one into another." 



