MOUNT WILSON OBSERVATORY. 233 



STAFF. 

 The Director has devoted much time to the project of developing 

 research in physics at the California Institute of Technology in coop- 

 eration with the Observatory. He has also undertaken an mvestiga- 

 tion of the combined effect of electric and magnetic fields on radiation 

 and continued his solar researches. Dr. Walter S. Adams, Assistant 

 Director, has given most of his attention to his investigations in stel- 

 lar spectroscopy. Professor Frederick H. Scares, superintendent of 

 the Computing Division and editor of the Observatory publications, 

 has advanced his stellar researches in various directions. Dr. Arthur 

 S. King, superintendent of the Physical Laboratory, has pursued 

 his work with the electric furnace. Dr. Charles E. St. John has con- 

 tinued his studies on the solar rotation, the spectrum of Venus, and 

 the wave-lengths of solar and terrestrial lines. Dr. J. A. Anderson 

 has investigated the effective wave-length of sunlight and starlight, 

 and the spectra of explosive discharges, and continued his tests of the 

 ruling machine with Mr. Jacomini. Dr. Harlow Shapley, who has 

 gone on with his work on variable stars and globular clusters, left for 

 the Harvard College Observatory in March on a year's appointment. 

 Mr. Harold D. Babcock has given most o^ his time to the comparison 

 of solar and laboratory wave-lengths and the measurement of pressure 

 shifts. Mr. Francis G. Pease, in addition to his work on instrument 

 design, has measured star diameters with the 20-foot interferometer. 

 Dr. Paul W. jNIerrill has continued his investigations on long-period 

 variable stars and the spark spectrum of air. Mr. Ferdinand Ellerman 

 has made regular solar observations and served as Observatory 

 photographer. Dr. Adriaan van Maanen has continued his investi- 

 gations on trigonometric parallaxes and on proper motions of stars 

 and motions in spiral nebulse. Professor Alfred H. Joy, secretary of the 

 Observatory, has taken part in the stellar spectroscopic work. Dr. 

 John C. Duncan, who has spent a year at the Observatory, has made 

 photographs of nebulse and joined in stellar spectroscopic observa- 

 tions. Dr. Seth B. Nicholson has continued his observations of the sun 

 and Venus, and has begun laboratory experiments with thermopiles. 

 Dr. Gustav Stromberg has continued his work in stellar spectroscopy, 

 with particular reference to theoretical investigations. Dr. R. F. 

 Sanford has also taken part in the stellar spectroscopic work. Mr. 

 Edwin P. Hubble has been engaged in the photographic and spectro- 

 scopic study of nebulse and nebulous stars. Dr. Bertil Lindblad, of 

 the University of Upsala, has been at the Observatory as volunteer 

 assistant since October and has carried on investigations dealing with 

 the determination of the absolute magnitudes of faint stars by spec- 

 troscopic methods. Dr. H. C. Wilson, of Carleton College, spent the 

 months between September and June at the Observ^atory and devoted 

 his time to the measurement of Unes in the sun-spot spectrum and 

 a number of stellar spectra. Mr. Edison Pettit, who joined the staff 



