Appendix V. 



REPORT OF THE OPERATIONS OF THE ASTROPHYSICAL OBSERVA- 

 TORY FOR THE YEAR ENDING JUNE 30, 1905. 



Sir : The equipment of the Astropbysical Observatory is now valued as 

 follows : 



Buildings $7, 400 



Apparatus 45, 300 



Library and records 7,200 



During tbe year three wooden shelters, covering, respectively, the coelostat, 

 the long focus concave mirror, and the holographic outfit for observing the solar 

 image, have been erected at a cost of $1,135. This item is chargeable to the 

 appropriation for the fiscal year ending June 30, 1904. The fence around the Ob- 

 servatory lot has been renewed at a cost of $554. By permission of the park 

 authorities the Observatory inclosure was at the same time enlarged on the 

 east and south, and now contains 15,300 square feet. 



Apparatus chiefly for use in a proposed expedition to a high altitude observ- 

 ing station has been procured at a cost of $3,862. Of this sum, $2,527 is 

 chargeable to the appropriation for the fiscal year ending June 30, 1904. Usual 

 periodicals have been continued, a few books of reference have been purchased, 

 and about 118 volumes have been collated and bound, at a total cost of $369. 



No losses of property beyond usual wear and tear have occurred during the 

 year. 



Changes in personnel. — In the latter half of 1904 Dr. S. A. Mitchell was em- 

 ployed three months as temporary assistant on stellar radiation experiments. 



Richard Norris resigned March 31. 1905. 



By request of the Chief of the Weather Bureau Mr. H. H. Kimball was 

 assigned to the Observatory temporarily for a period beginning May 1, 1905, 

 in order that he might learn the methods of holographic observation employed 

 here. 



Mr. L. R. Ingersoll was engaged for three months, beginning May 10, 1905, as 

 temporary assistant for the Mount Wilson expedition. 



Joseph Dwyer. messenger, was engaged April 1, 1905. 



WORK or THE OBSERVATORY. 



For convenience I describe the work of the Observatory under the following 

 headings : 



(1) Observations at Washington on the variability of the sun. 



(2) Miscellaneous work. 



(3) Expedition to Mount Wilson in California. 



(1) OBREKVATIOXS AT WASHINGTON ON THE VARIABILITY OF THE SUN. 



As indicated in your paper, " On a possible variation of the solar radia- 

 tion," o and summarized in my last year's report, our observations of several 

 years, but especially of the year 1903, have tended to produce the belief that 

 the total radiation of the sun may vary in comparatively brief periods, these 

 variations of solar radiation being irregular in period, but tolerably frequent 



a Astropbysical Journal, June, 1904, and London, Edinburg, and Dublin 

 Philosophical Magazine, July, 1904. 



74 



