LITERARY NOTICES. 



!33 



results which he reached were at once ac- 

 cepted as valid advances in the fields of Phys- 

 ics, Chemistry, and Physiology. But, in re- 

 gard to the study of the radiations and the 

 new results attained in that field, matters 

 took a different turn. There was a long se- 

 ries of quiet preliminary inquiries that paved 

 the way for the splendid demonstrations of 

 spectrum analysis, but which were unappre- 

 ciated and thrown into the shade after that 

 brilliant discovery. A new epoch seemed to 

 be suddenly created, and men cared little to 

 know who had gone before and prepared 

 for it. Unfortunately, this condition of things 

 was favorable to the misappropriation of re- 

 sults gained by pioneer laborers. As the 

 conductors of the " Philosophical Magazine " 

 were of course aware of what had appeared 

 in their pages, and were familiar with the 

 early history of this train of researches, we 

 had not much doubt that they would speak 

 to the point when the time came. Our read- 

 ers will observe that in the subjoined notice 

 of Dr. Draper's work they have done so, 

 thus decisively confirming the positions 

 that we have formerly taken in regard to 

 the priority of Dr. Draper in the investiga- 

 tions that led up to spectrum analysis. 



Dr. Draper here brings together the 

 scattered memoirs and essays that he has 

 written during the past forty years on sub- 

 jects connected with radiation and radiant 

 energy. They are thirty in number, and, 

 for the most part, are simply reprints ; but 

 in a few cases the original memoirs are 

 condensed, and in one or two cases the 

 article here given is the substance of a 

 considerable number of detached articles. 

 Most of them have already appeared in our 

 pages ; the earliest of them, on subjects re- 

 lating to photography, appeared in 1840. 

 " I have endeavored," the author tells us, 

 " to reproduce these memoirs as they were 

 originally published. When considerations 

 of conciseness have obliged me to be con- 

 tented with an abstract, it has always been 

 so stated, and the place where the original 

 may be found has been given. Sometimes, 

 the circumstances seeming to call for it, ad- 

 ditional matter has been introduced ; but 

 this has always been formally indicated 

 under the title of ' Notes,' or included in 

 parentheses" (p. x.). 



It is probably known to our readers 



that Count Rumford made a donation to 

 the American Academy of Arts and Science 

 (similar to that which he made to the Royal 

 Society) for rewarding discoveries and im- 

 provements relating to light and heat made 

 in America. The Academy has been rather 

 chary of bestowing its honors, and had only 

 awarded its Rumford Medal four times be- 

 fore it made the award in 1875 to Dr. J. 

 W. Draper " for his researches in radiant 

 energy." This circumstance has deter- 

 mined the selection of articles in the pres- 

 ent volume. It comprises the researches 

 on which the award was founded. 



The President's statement of the grounds 

 of the award is given in the Appendix, and 

 may be summarized as follows : 



(a.) Independent discovery of Moser's 

 images. 



(b.) Measurement of the intensity of 

 chemical action of light, by exposing to 

 the source of light a mixture of equal vol- 

 umes of chlorine and hydrogen. 



(c.) Application of Daguerreotype pro- 

 cess to taking portraits. 



(d.) Application of ruled glasses and 

 specula to produce spectra for the study 

 of the chemical action of light. 



(e.) Investigation of the nature of the 

 rays absorbed by growing plants in sun- 

 light. 



(/.) Discussion of the chemical action 

 of light, and proof that rays of all wave- 

 lengths are capable of producing chemical 

 changes. 



(g.) Researches on the distribution of 

 heat in the spectrum. 



And, finally, an elaborate investigation, 

 published in 1847, by which he established 

 the following facts, which we will give in 

 the words of the award : 



1. All solid substances, and probably liquids, 

 become incandescent at the same temperature. 



2. The thermometric point at which sub- 

 stances become red-hot is about 977 Fahr. 



3. The spectrum of an incandescent solid is 

 continuous ; it contains neither bright nor dark 

 fixed lines. 



4. From common temperatures, nearly up to 

 977 Fahr., the rays emitted by a solid are invisi- 

 ble. At that temperature they are red ; and the 

 heat of the incandescing body being made con- 

 tinuously to increase, other rays are added, 

 increasing in refrangibility as the temperature 

 rises. 



5. While the addition of rays, so much the 

 more refrangible as the temperature is higher, 



