188 CARNEGIE INSTITUTION OF WASHINGTON. 



St. John. Miss Burwell, Miss Shumway, and for a part of the time, 

 Miss Brayton, have made measures and reductions relating to stellar 

 spectroscopy. Miss Richmond, Miss Joyner, Miss Winn, and Miss 

 Davis, and, for a part of the year, Miss Carolyn Burns and Miss 

 Helen Burns, have been occupied with stellar photometry. Miss 

 Wolfe has given her time to reductions of stellar parallax and the 

 sun's general magnetic field. She has also done miscellaneous com- 

 puting and photographic work, and has assisted in the library. Miss 

 Margherita Burns and Miss Brayton have both given part of their 

 time to the work of the Physical Laboratory, although during recent 

 months Miss Burns has assisted Dr. St. John, and, to some extent, 

 Dr. Adams. Miss Connor has continued as librarian and has assisted 

 with the editorial work. 



Dr. John C. Duncan, director of the Whitin Observatory of Welles- 

 ley College, took part in photographic and stellar spectrographic work 

 during the summer of 1918. Mrs. Harlow Shapley, who has continued 

 her ser\dce as a volunteer assistant, has collaborated with Dr. Shapley 

 in his various stellar investigations. Miss Edna Carter, associate pro- 

 fessor of physics at Vassar College, has continued to serve as volunteer 

 assistant in the Physical Laboratory, where she has devoted her time to 

 the further study of metallic spectra produced by the cathode discharge. 

 Mr. Hugo Benioff has served as volunteer assistant on Mount Wilson. 



Mr. L. B. Aldrich had charge of the observations at the Smithsonian 

 Astrophysical Observatory on Mount Wilson during the summer of 



1918. 



INVESTIGATIONS IN PROGRESS. 



SOLAR RESEARCH. 



The permanent instrumental equipment for solar work has been 

 increased by the construction of a special form of stereoscope, de- 

 signed for the combination of spectroheliograms of the hydrogen 

 fiocculi. Apparatus employed in an attempt to detect the corona in 

 sunlight with photo-electric cells has been improvised, chiefly by 

 utilizing accessories of the Koch registering microphotometer. The 

 instruments used by the eclipse expedition were adapted from the 

 equipment on Mount Wilson and that of the Physical Laboratory. 



SOLAR PHOTOGRAPHY, 



During the year ending August 31, 1918, the following solar photo- 

 graphs were taken with the 60-inch tower telescope by Messrs. EUer- 

 man, Nicholson, Joy, Dockham, and Benioff: Photoheliograms of 

 6.5-inch image, 345 on 318 days; spectroheliograms with 5-foot spec- 

 troheliograph (Ha, entire 6.5-inch disk), 221 on 221 days; spectro- 

 heliograms with 13-foot spectroheliograph (K and Ha, 2-inch disk 

 and prominences; Ha, portions of 6.5-inch disk, monochromatic light 

 from continuous spectrum), 1,881. 



