390 THE POPULAR SCIENCE MONTHLY. 



heat wMch. accompanied its beams, and brought something more 

 necessary to our life and that of all nature than the light itself. 



The idea that not only mankind, but nature, would perish 

 though the light continued, if this was divorced from heat, made 

 a profound impression, he tells us, on his childish mind. The 

 statement that such an idea could enter with dominating force 

 into the mind of a child will perhaps seem improbable to most. 

 It will, however, be comprehensible enough to some here, I have 

 no doubt. 



Is there some ornithologist present who remembers a quite in- 

 fantile attraction which birds possessed for him above all the rest 

 of the animated creation ; some chemist whose earliest recollec- 

 tions are of the strange and quite abnormal interest he found as a 

 child in making experimental mixtures of every kind of accessible 

 household fluid and solid ; some astronomer who remembers when 

 a very little creature that not only the sight of the stars, but of 

 any work on astronomy, even if utterly beyond his childish com- 

 prehension, had an incomprehensible attraction for him ? I will 

 not add to the list. There are, at any rate, many here who will 

 understand and believe Melloni when he tells how this radiant 

 heat, commonplace to others, was wonderful to his childish 

 thought, and wrought a charm on it such that he could not see 

 wood burn in a fireplace, or look at a hot stove, without its draw- 

 ing his mind, not to the fire or iron itself, but to the mysterious 

 effluence which it sent. 



This was the youth of genius ; but let not any fancy that genius 

 in research is to be argued from such premonitions alone, unless 

 it can add to them that other qualification of genius which has 

 caused it to be named the faculty of taking infinite pains. Mel- 

 loni's subsequent labors justified this last definition also ; but I 

 can not speak of them here, further than to say that, after going 

 over a large part of his work myself, with modern methods and 

 with better apparatus, he seems to me the man, of all great stu- 

 dents of our subject, who, in reference to what he accomplished, 

 made the fewest mistakes. 



Melloni is very great as an experimenter, and owes much of 

 his success to the use of the newly invented thermopile, which is 

 partly his own. I can here, however, speak only of his results, 

 and of but two of these — one generally known ; the other, and the 

 more important, singularly little known, at least in connection 

 with him. The first is the full recognition of the fact, partly an- 

 ticipated by De la Eoche, that radiant heat is of different kinds, 

 that the invisible emanations differ among themselves just as 

 those of light do. Melloni not only established the fact, but in- 

 vented a felicitous term for it, which did a great deal to stamp it 

 on recognition — the term " thermochrose," or heat-color, which 



