D ] 



Notices respecting New Books. 211 



15265, 15865, 16489, 17086, and 16827. Hence the discre- 

 pancy between equation (7) and experiment is not great even 

 for temperatures so high as 240° ; while for a maximum tem- 

 perature under 150° or so the discrepancy is practically nil. 



[To "be continued.] 



XXXV. Notices respecting New Books. 



Scientific Memoirs ; being experimental Contributions to a J£noivledge 

 of Radiant Energy. By John William Draper, M.D., LL.D., 



$c. Sfc. New York : Harper and Brothers. 1878 (8vo, pp. 473). 



|E. DRAPER here brings together the scattered memoirs and 

 essays that he has written during the past forty years on 

 subjects 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 relating to Photo- 

 graphy, appeared in 1840. " I have endeavoured," 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, additional matter has been in- 

 troduced ; 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 dis- 

 coveries and improvements relating to light and heat made in 

 America. The Academy has been rather chary of bestowing its 

 honours, and had only awarded its Rumford Medal four times before 

 it made the award in 1875 to Dr. J. W. Draper " for his researches 

 in Radiant Energy." This circumstance has determined the se- 

 lection of articles in the present volume. It comprises the re- 

 searches 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. 



(6) Measurement of the Intensity of the Chemical Action of 

 Light by exposing to the Source of light a mixture of Equal Vo- 

 lumes of Chlorine and Oxygen. 



(c) Application of Daguerreotype process to taking portraits. 



(d) Application of ruled glasses and speculate produce Spectra 

 for the study of the Chemical Action of light. 



(e) Investigation of the nature of the rays absorbed by growing 

 plants in sunlight. 



