REPORT OF THE SECRETART 89 



WORK IN THE FIELD 



As far as weather permitted, daily observations of the solar con- 

 stant of radiation were continued at three stations : Tyrone, N. Mex., 

 Table Mountain, Calif., and Montezuma, Chile. Criticism having 

 been made again from foreign sources regarding the temperature 

 coefficient of the silver-disk pyrheliometer, numerous redetermina- 

 tions of this quantity were made at Tyrone and Table Mountain. 

 Owing to a misapprehension of directions, no less than 120 redeter- 

 minations were made at Tyrone by Messrs. Moore and Froiland. 

 Their mean is identical with that found previously by Abbot and 

 Aldrich at Washington, and by Zodtner and Greeley at Table Moun- 

 tain, and is almost identical with that found this year by Butler 

 and Greeley at Table Mountain. Over 200 determinations have now 

 been made, giving as their mean the same temperature correction 

 which has been used for nearly 30 years with silver-disk pyrheli- 

 ometers. There can now be no further question of altering it. 



PERSONNEL 



No changes in pei^oniiel have taken place since my last report, 

 except that L. A. Fillmen, for 10 years instrument maker under 

 private compensation in the Division of Radiation and Organisms, 

 has been appointed instrument maker under the public funds at the 

 Astrophysical Observatory, succeeding A. Kramer, retired. 

 Respectfully submitted. 



C. G. Abbot, Director. 

 The Secretary, 



Smithsonian Institution. 



