REPORT OF COMMITTEE ON OBSERVATORIES 1 43 



of the highest value to secure for this enterprise the cooperation of 

 another southern observatory in addition to that of the Cape, this 

 also to be provided with a 7 or 8-inch heliometer. In my opinion, 

 this is the only instrument with which, up to the present time, one 

 has been able to secure reliable determinations of parallax. 



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With these remarks I have desired to express my personal and 

 lively interest in the plans of the Carnegie Institution, for which I 

 wish a speedy and complete fulfilment. I leave to you to com- 

 municate to your fellow members of the Committee so much of this 

 letter as you think best, but otherwise I desire that you will con- 

 sider it a private answer to your communication. 



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II. CORRESPONDENCE RELATING TO PROPOSED 

 SOLAR OBSERVATORY. 



Introduction. 



In January, 1903, a confidential statement regarding a proposed 

 solar observatory was sent by the Secretary of the Committee to a 

 number of astronomers and physicists. This letter stated that the 

 principal purposes of the observatory, as they then appeared to the 

 Committee, would be to investigate (1) the intensity of the solar 

 radiation and its possible changes during a sun spot period ; (2) the 

 problem of the solar constitution, through observations with the 

 spectroscope and other instruments ; and (3) various stellar and 

 nebular problems connected with the evolution of the sun and stars. 

 The necessity of choosing sites especially suited for such work was 

 also pointed out, and the suggestion was made that for the study of 

 the solar constant a high mountain station, with a second station 

 near the base of the mountain, might be required. Suggestions 

 were requested regarding the proposed program of work, the selec- 

 tion of sites, and any other subjects connected with the observatory. 



In response to this letter the following replies were received : 



Letters from Correspondents. 



\from Professor C. A. Young-, Director of the Observatory, 



Princeton, N. /.] 



February 7, 1903. 

 Naturally I am very much interested in the question of a special 

 astrophysical observatory. There is no question that the lines of 



