ELECTRICITY, MAGNETISM, AND GBAVITATION. 91 



bility one into another, or as being simply modifications of 

 one universal force, we need but one. 



A paper by Professor Draper, has just been published by 

 M. Melloni, and brought forward by him as still further cor- 

 roborating the analogy of light and heat. 



It is highly interesting in this paper to witness the re* 

 markable accuracy with which the development and results 

 of light and heat correspond, by the increase or decrease in 

 temperature of a slip of platinum heated to incandescence 

 by voltaic agency. Professor Draper has given three columns 

 in his table, one showing the degrees of expansion of thepla- 

 tina hy the voltaic current, a second exhibiting the intensity 

 of light, and another that of the heat given off, as shown by 

 that delicate instrument the thermo-multiplier. So constant 

 are the three existences in their corresponding developments, 

 that M. Melloni says "they follow in the progression of 

 quantity the same analogy they do in the progression of 

 quality." Now, it is remarkable that the facts exhibited in 

 two columns should be emphatically noticed, and yet no 

 observation should be made upon the analogy of the third 

 — that the very circumstances which to the mind of this great 

 philosopher evince the perfect identity of light and heat, should 

 be unobserved and unrelated as regards the results of the first 

 column, or electricity. 



If the correspondence of the results developed give strong 

 reason to believe that light and heat are analogical, surely 

 the corresponding results of the force from which they are 

 developed, declare equally its identity, of which M. Mel- 

 loni remarks, "the quantities of light emitted by a strip 

 of platina," brought (thus) to difierent degrees of incan- 

 descence, '' is the only one by which we could hope for a 

 successful result." * 



* After several years of quiet, thoughtful meditation and experiment 

 upon the phenomena of light, heat, electricity, &c., I see no reason to alter 



