2l8 REPORTS OF INVESTIGATIONS AND PROJECTS. 



prisms purchased under the above grant on the Crocker eclipse expedition to 

 Flint Island. After spending several months in mounting these in a tempo- 

 rary wooden spectrograph suitable for the purpose, Professor Lewis sailed 

 with the expedition November 22, 1907. The expedition was entirely suc- 

 cessful, as shown in the report published in Lick Observatory Bulletin No. 

 131. The results obtained with the quartz spectrograph are published in 

 detail in that bulletin. An excellent spectrum of the corona was obtained, 

 showing at least two new and intense lines, undoubtedly of coronal origin. 



Professor Lewis is now engaged in taking up the regular work of studying 

 the ultra-violet spectra of compounds. A number of films were made last 

 year, but the results are not yet reduced. 



Nichols, Edward L., Cornell University, Ithaca, New York. Grant No. 

 286. Quantitative study of Uiiorescence and phosphorescence, especially 

 at low temperatures. (For previous reports see Year Books Nos. 4, 5, 

 and 6.) $1,000. 



The investigations carried on during the year 1907-08 may be summarized 

 briefly as follows : 



(o) The B.vperimental Study of Cathodo-hunincscence, by Professors 

 Nichols and Merritt. — This work consists of a preliminary exploration of an 

 important field in which hitherto little or no quantitative investigation has 

 been carried out. Definite results have been obtained and several general 

 principles have been established which serve as a basis for further study. 

 The results are in preparation for publication in the Physical Review. 



(6) The Quantitative Study of Thermo-luminesccnce, by Dr. C. A. 

 Pierce. — This work, which forms the subject of two papers* in the Physical 

 Review, afifords the first systematic quantitative investigation of the relations 

 which govern thermo-luminescence, together with suggestive theoretical de- 

 ductions. The research is being further pursued by Mr. Pierce, who is ap- 

 plying to the same a new and interesting photographic method of attack. 



(c) The Bifect of Temperature upon the Absorption and Fluorescence of 

 Solids, by Mr. R. C. Gibbs. — This work, which will ultimately be extended 

 to various substances and will cover a wide range of temperature, has been 

 completed so far as the study of the effect of high temperatures upon the 

 absorption and fluorescence of uranium glass is concerned. Mr. Gibbs's re- 

 sults, which will appear in the Physical Review, afford a complete and inter- 

 esting graphical representation of the changes in the absorption bands of this 

 substance as the result of heating and of the corresponding modifications in 

 the character of the fluorescence spectrum. The spectrum is found to con- 

 sist of several overlapping bands, some of which vanish gradually as the 

 temperature rises, while others are comparatively unaffected. The result is a 

 striking modification of the composition of the fluorescent light. 



* C. A. Pierce : The Physical Review, vol. xxvi. No. 4. and vol. xxvi, No. 6. 



