MOUNT WILSON OBSERVATORY. 183 



grating previously in use. It is with much anticipation and hope that the 

 Observatory looks forward to the results to be attained from the use of the 

 products of this successful ruling-engine. 



STAFF. 



Dr. George E. Hale, who has been abroad during the year for a rest neces- 

 sitated by illness, resigned the Directorship on July 1. He has been ap- 

 pointed Honorary Director and will retain his previous relationship to 

 problems of research and all matters of general policy. Dr. Walter S. Adams 

 was appointed Director in charge of operations on July 1 and will continue 

 his investigations in stellar spectroscopy. 



Professor Frederick H. Scares, editor of the Observatory publications 

 and superintendent of the Computing Division, has been engaged in researches 

 in stellar photometry and related subjects. Dr. Arthur S. King, super- 

 intendent of the Physical Laboratory, has continued his studies of spectra 

 produced in the electric furnace and the appHcations of ionization phenomena. 

 Dr. Charles E. St. John's investigations have dealt with measurements of 

 wave-lengths in the sun and arc and the solar rotation. Dr. J. A. Anderson 

 has extended his studies of the spectra of explosive discharges and has 

 carried on tests of the diffraction gratings ruled by Mr. Jacomini. Mr. Harold 

 D. Babcock has completed his researches on the Zeeman effect for several 

 elements and has measured wave-lengths irt the laboratory with interference 

 apparatus. Mr. Francis G. Pease has continued measurements of the diam- 

 eters of stars with the 20-foot interferometer and has devoted much time to 

 the design of apparatus, especially that to be used at the solar eclipse. Dr. 

 Paul W. Merrill has completed his investigation of the radial velocities of the 

 long-period variables and is making a study of the physical characteristics 

 of their spectra. Dr. Adriaan van Maanen has been engaged in measure- 

 ments of the parallaxes and proper motions of stars and of the internal motions 

 in spiral nebulae. Professor Alfred H. Joy, secretary of the Observatory, has 

 continued his determinations of radial velocity and spectroscopic parallaxes 

 and has made special studies of the spectra of certain variable stars. Dr. 

 Gustav Stromberg has carried on investigations of stellar motions in space. 

 Dr. Seth B. Nicholson has been engaged in solar investigations and measure- 

 ments of stellar and planetary radiation with thermo-couples. Mr. Ferdi- 

 nand Ellerman has continued solar observations and has remained in charge 

 of the general photographic work of the Observatory. Dr. Roscoe F. San- 

 ford has completed his measurements of the radial velocities of R-type stars 

 and has determined the orbits of several spectroscopic binaries. Dr. Edwin 

 Hubble has made a study of the forms of nebulae for the purpose of classi- 

 fication and has extended his researches on the source of luminosity in nebulae. 

 Dr. Edison Pettit has made solar observations and measurements of solar, 

 stellar, and planetary radiation with thermo-couples. Mr. Milton L. Huma- 

 son has continued the study of the spectra and radial velocities of the stars 

 in the Selected Areas and has made direct photographs of numerous nebulae 

 and other objects. Mr. Wendell P. Hoge, night assistant with the 60-inch 

 telescope, has shared in the stellar spectroscopic work. Mr. Joseph P. 

 Hickox has carried on solar observations and has assisted in general pho- 

 tography. Mr. Hickox resigned on July 1 and Mr. Lewis H. Humason was 

 appointed to his position. Mr. Sinclair Smith has assisted in the laboratory 



