*34 



THE POPULAR SCIENCE MONTHLY. 



in taking place, there is an increase in the in- 

 tensity of those already existing. The award 

 then proceeds as follows : Thirteen years after- 

 ward Kirchhoff published his celebrated memoir 

 on the relations between the coefficients of emis- 

 sion and absorption of bodies for light and heat, 

 in which he established mathematically the same 

 facts, and announced them as new. 



We are, of course, aware that this is 

 rather a burning question ; but, whatever 

 may be thought of the justice of these 

 claims, there can be no doubt that the fact 

 of their having been made on behalf of Dr. 

 Draper by so distinguished a body as the 

 American Academy of Arts and Science 

 ought to be known, and that its judgment 

 will receive at least respectful consideration 

 whenever the early history of spectroscopic 

 science comes to be written. And it is im- 

 possible not to draw attention to this fact in 

 a notice, however brief, of Dr. Draper's vol- 

 ume ; for, plainly, one of the motives of its 

 publication is to assert his claims to priority 

 of discovery in regard to the points above 

 quoted. In fact, the four memoirs which 

 bear 'directly on the subject of spectrum 

 analysis are printed first in the volume, 

 and are followed by a note in which Dr. 

 Draper complains, though in very decorous 

 language, that he has received considerably 

 less than justice at the hands of M. Kirch- 

 hoff; and, by way of showing that he has 

 tangible grounds for complaint, he makes 

 the following quotations (p. 85) from M. 

 Jamin's " Cours de Physique," in which re- 

 sults that he had previously established are 

 formally attributed to M. Kirchhoff: 



M. Kirchhoff has deduced the following im- 

 portant consequences : 



Black bodies begin to emit at 977 Fahr. red 

 radiations, to which are added successively and 

 continuously other rays of increasing refrangibil- 

 ity as the temperature rises. 



All substances begin to be red-hot at the same 

 temperature in the same inclosure. 



The spectrum of solids and liquids contains 

 no fixed lines.* 



Now, it may be said with very little qual- 

 ification that what is here attributed to M. 

 Kirchhoff is to be found distinctly stated in 

 the first memoir in the volume before us, 

 which was published by Dr. Draper in 1847. 

 By experimenting with a strip of platinum 

 heated by the transmission of a current 



* The above quotation is, we presume, to be 

 found on pp. 463, 464, vol. iii., edition of 1866. If 

 so, it is not exactly a quotation, but is made up 



whose force could be regulated, he ascer- 

 tained that the temperature at which red 

 rays are first radiated is 977 Fahr. He 

 also ascertained that platinum, brass, anti- 

 mony, gas-carbon, and lead became incan- 

 descent at the same time with the iron bar- 

 rel in which they were gradually heated, and 

 that the apparent exceptions presented by 

 chalk, marble, and fluor-spar were due to 

 phosphorescence. By raising the tempera- 

 ture of the platinum wire and analyzing 

 with a prism the light emitted, he proved 

 that the length of its spectrum gradually 

 increased with the temperature until at 

 2130 Fahr. the full spectrum of daylight 

 was attained ; and it is clear that he re- 

 garded the result thus obtained as being gen- 

 erally true. That the spectrum of the in- 

 candescent platinum contained no dark lines 

 had indeed come out only incidentally in the 

 course of the investigation ; still it was not 

 by any means a point seen but not observed ; 

 for, in consequence of observing it, he re- 

 sorted to a comparison of the spectra of in- 

 candescent platinum at different tempera- 

 tures with the spectrum of daylight in order 

 to determine their extent, instead of fixing 

 their extent by the dark lines of the spectra 

 themselves, which he had ascertained to 

 be non-existent. On the whole, the above 

 statement breaks down at nearly every point. 

 What is therein referred to M. Kirchhoff was 

 certainly ascertained before by Dr. Draper. 

 Whether Dr. Draper was the first person to 

 observe all these points is a very different 

 question, and one we would by no means 

 prejudge ; indeed, without going beyond the 

 limits of the first Memoir, it is pretty plain 

 that the temperature of incandescence was 

 known with considerable accuracy before 

 Dr. Draper's experiment with the platinum 

 wire ; and it certainly was believed (if not 

 proved) that the temperature was the same 

 for all bodies. 



Habit and Intelligence. A Series of Es- 

 says on the Laws of Life and Mind. 

 By Joseph Joiin Murphy. New York : 

 Macmillan & Co. Pp. 583. Price, $5. 

 The first edition of this work appeared 



of parts of a much larger statement. We may 

 also observe that Memoir I. of the present vol- 

 ume is not in all respects an exact verbal reprint 

 of this Memoir published in our " Journal "' for 

 May, 1847. This does not, however, affect the 

 point at issue. 



