184 CARNEGIE INSTITUTION OF WASHINGTON. 



and has carried on studies of the spectrum of exploded wires. He has also 

 aided Dr. Michelson in his investigations. Mr. John L. Ridgway has been 

 connected with the staff during several months of the year, and has been 

 engaged in making drawings of sun-spots, showing their positions, polarities, 

 and field-strengths. 



In the Computing Division, Miss Mayberry has been engaged in the meas- 

 urement of the wave-lengths of lines in the spectrum of sun-spots in con- 

 nection with Dr. Hale's solar investigations. Miss Ware and Mr. Edward 

 F. Adams have assisted Dr. St. John in the determination of wave-lengths of 

 solar lines and of the solar rotation. Miss Joyner and Miss Richmond have 

 been associated with the photometric studies of Professor Scares, and Mrs. 

 Marsh has aided Dr. van Maanen in his observations of the parallaxes and 

 proper motions of stars. The measurement and reduction of stellar spec- 

 trograms have been carried on by Miss Brayton, Miss Burwell, Miss Fretz, 

 Miss Poole, and Miss Wiberg. Miss Brayton has also assisted in the reduc- 

 tion of the measurements of stellar radiation. Miss Shumway resigned 

 her position on September 1 after 12 years of service in this department of the 

 Observatory. Miss Keener has devoted all of her time to the work of the 

 Physical Laboratory. Miss Connor has remained in charge of the library 

 and has assisted in much of the editorial work. 



Dr. Knut Lundmark, of the Observatory of Upsala, who came to the 

 Observatory as a volunteer assistant on June 1, 1922, remained until May 1 

 of the present year. He carried on numerous investigations on the color 

 indices of the spiral nebulae and of faint stars, the distribution of novae, 

 and related problems. Mr. John A. Carroll, Isaac Newton student of Cam- 

 bridge University and Research Fellow in Physics in the Norman Bridge 

 Laboratory of the California Institute of Technology, has carried on certain 

 investigations in the Physical Laboratory dealing with the absorption spec- 

 trum of hydrogen. Mr. H. H. Plaskett, of the Dominion Astrophysical 

 Observatory, spent the month of June at the Observatory. Professor I. 

 Yamamoto, of the Observatory of Kyoto, became a volunteer assistant 

 in July 1923 and has been engaged in solar investigations. 



Dr. A. A. Michelson, of the University of Chicago, Research Associate, 

 spent the period between June 15 and August 15 at the Observatory and 

 has continued his investigation of the velocity of light. Dr. Henry Norris 

 Russell, of Princeton University, Research Associate, passed the months 

 of May and June in Pasadena and was engaged in several investigations, 

 including series relationships in spectra, the masses of stars, and pressure 

 in the solar atmosphere. 



The appointment of Professor J. H. Jeans as Research Associate from 

 December 1, 1922, is a matter of the deepest interest to the Observatory. 

 The opportunity to secure the benefit of his wide knowledge of the problems 

 of cosmogony and stellar dynamics is proving of the greatest value to the 

 members of our scientific staff. 



OUTLINE OF THE YEAR'S WORK. 



The scientific activities of the Observatory have been continued through- 

 out the year with results of marked interest and importance in every depart- 

 ment of work. Among these, reference may be made to Anderson's extension 

 of his method of wire explosions, to his use of the vacuum spark, and to the new 



