MOUNT WIIvSON SOLAR OBSERVATORY. 1 75 



of Stellar Spectroscopy. Prof. F. H. Scares has remained in charge of the 

 Computing Division and the editorial work, and has carried forward his re- 

 searches in stellar photometry with the 6o-inch reflector. He has also made 

 a trip to Europe, to investigate the possibilities of improving photographic 

 processes. Dr. Arthur S. King has continued his investigations as super- 

 intendent of the physical laboratory. Dr. C. E. St. John has been engaged 

 in spectroscopic work on the sun with the 6o-foot and 150- foot tower tele- 

 scopes. Mr. Ferdinand Ellerman, Dr. Arnold Kohlschiitter, and Mr. Charles 

 Backus have continued the daily observations with the 5-foot spectrohelio- 

 graph. Mr. Ellerman and Dr. Kohlschiitter have also assisted the Director 

 in work with the 150- foot tower telescope. Mr. H. D. Babcock has carried 

 on a variety of laboratory investigations, and has been associated with the 

 Director in attempts to detect the general magnetic field of the sun and 

 nebulae. Mr. F. G. Pease has continued his systematic photographic study 

 of nebulae and star-clusters with the 60-inch reflector, in addition to his work 

 of designing instruments. Dr. E. A. Fath has been engaged in several in- 

 vestigations with the 60-inch reflector, and has photographed the spectrum 

 of the Milky Way with a low-dispersion spectrograph kindly loaned by Di- 

 rector Campbell, of the Lick Observatory. On account of his appointment 

 as professor of astronomy at Beloit College, he resigned from the Observa- 

 tory staff on September i. Dr. Arnold Kohlschiitter, who was appointed 

 assistant January i, has devoted most of his time to stellar spectroscopic 

 observations and the classification of stellar spectra. 



Prof. J. C. Kapteyn, Research Associate of the Carnegie Institution of 

 Washington, spent the months of July, August, and September on Mount 

 Wilson in continuation of his studies of star-streams and related problems. 

 Prof. E. E. Barnard, of the Yerkes Observatory, made visual and photo- 

 graphic observations of Mars and Saturn with the 60-inch reflector during 

 November and a part of December. Prof. Carl Stormer, of the University 

 of Christiania, Research Associate of the Carnegie Institution of Washing- 

 ton, who visited the Observatory during June and July, has made a mathe- 

 matical investigation of the distribution of ions in the solar atmosphere as 

 affected by the magnetic field in sun-spots. Prof. Ejnar Hertzsprung, of 

 the Potsdam Observatory, is staying on Mount Wilson from July to October 

 for the purpose of measuring the effective wave-length of faint stars with 

 the aid of a large grating, used in conjunction with the 60-inch reflector. 

 Dr. J. A. Anderson, on leave of absence from the Johns Hopkins University, 

 arrived in Pasadena on September 10. He will superintend the construction 

 of a ruling machine for diffraction gratings, designed by himself and Mr. 

 Pease. Mr. P. J. Van Rhyn, of Groningen, Holland, joined the Observatory 

 as a volunteer assistant in July, and Dr. Adrian Van Maanen, a graduate of 

 the University of Utrecht, spent some weeks on the mountain in the same 

 capacity during July and August. On September i Dr. Van Maanen was 

 appointed a member of the Observatory staff. 



12 — YB 



