MOUNT WILSON OBSERVATORY. 



George E. Hale, Honorary Director. 

 Walter S. Adams, Director. 



The announcement on July 1 of the resignation of Dr. Hale as Director 

 of the Observatory was received with deep regret by everyone associated 

 in any way with its activities. The entire conception of the Observatory, its 

 development, the scope of its scientific research, its equipment, and methods 

 of investigation are to so large an extent a direct product of Dr. Hale's fore- 

 sight and his ability in the organization and conduct of research that any 

 change in his relationship to the Observatory is necessarily a matter for 

 profound concern. Fortunately, through a division of the responsibilities 

 connected with its administration, the Observatory will continue to receive 

 the most vital portion of the contribution which Dr. Hale has made to its 

 progress and success during the years of its existence. Although the con- 

 dition of his health requires him to lay down the burden of the direct conduct 

 of the operative side of the Observatory, he will, as Honorary Director, 

 retain his former relationship to all matters of general policy, the problems 

 of research, and the development of new methods and new instruments. 

 Of more importance than all else to the members of the staff will be the con- 

 tinuance of his personal influence and the inspiration afforded by his broad and 

 active interest in every form of scientific investigation. 



The Observatory has profited greatly during the year from the visits of 

 its Research Associates, Dr. A. A. Michelson and Dr. Henry Norris Russell, 

 and from its close relationship with the California Institute of Technology 

 and the scientists permanently or temporarily associated with it. Especial 

 reference should be made to the opportunity afforded to the members of the 

 staff to attend the series of lectures on atomic structure and the quantum 

 theory of spectral lines given during the winter at the California Institute 

 by Professor Sommerfeld of Munich. The intimate connection of many of 

 the investigations carried on in our physical laboratory, especially the tem- 

 perature classification of spectral lines by King and studies of the Zeeman 

 effect by Babcock, was brought out very clearly in these lectures. This 

 was emphasized even more fully by Russell, who, in the course of a series 

 of informal lectures to the members of the staff, showed how essential to the 

 solution of fundamental problems of series relationships in spectra is a knowl- 

 edge of the behavior of lines in the electric furnace, in the magnetic field in 

 sun-spots, and in stellar spectra. This close interrelationship of many of 

 the different branches of its work has been a marked feature in the scientific 

 progress of the Observatory. 



The preparations for the total solar eclipse of September 10, 1923, have 

 occupied much of the time of the scientific staff during the spring and summer 

 months, and the design and construction of the apparatus have been the chief 

 activity of the drafting department and the instrument shop during this time. 

 The favorable conditions under which the eclipse occurs, at a season of the 

 year and a time of day when clear skies may be expected, and with the edge 

 of the shadow path within less than 30 miles from Mount Wilson, have led to 

 the preparation of an unusually extensive plan for observations. Its prin- 

 cipal features are: first, the selection of sites for two expeditions, one at 

 Point Loma, near San Diego, well within the path of totality, and the other 



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