REPORT OF COMMITTEE ON OBSERVATORIES 149 



peuditure for such a purpose. Possibly a very moderate equipment 

 at the base would do all that is desirable. 



Might I also mention, in addition to the matters you speak about, 

 that a repetition of Duner's work on solar rotation in the reversing 

 layer is, I think, called for? I do not think the last word has been 

 said in that matter. 



{From Professor H. C. Vogcl, Director of the Royal Astrophysical 

 Observatory, Potsdam, Germany ^ 



[Translation.] 



February 19, 1903. 



In reply to your kind letter of Januarj' 15 in regard to the estab- 

 lishment of a great astrophysical observatory with stations at particu- 

 larly favorable points, I wish to repl}^ that I can only commend in 

 the warmest way the realization of this great undertaking in the 

 interests of science, and that I regard the investigations proposed by 

 you, on the subjects named below, as so suitable and exhaustive that 

 I am unable at present to suggest anything further : 



(i) Solar radiation problems, involving the measurement of the 

 solar constant at frequent intervals throughout the sun spot period. 



(2) Solar investigations, principally of a spectroscopic nature, 

 which require atmospheric conditions and instrumental facilities 

 superior to those hitherto emj)loyed. 



(3) Various stellar and nebular problems, such as could be under- 

 taken to the best advantage with the aid of a large reflecting tele- 

 scope. 



In Europe we are not so fortunately situated as to be able to find 

 so easily sites from which the proposed observations could be carried 

 out to advantage. We can therefore only wish success to our Ameri- 

 can colleagues if the Carnegie Institution should provide the means 

 necessary to carry out such comprehensive investigations, which 

 are so important for astrophysics. 



{From Professor H. Kayser, Director of the Physical histitiUe, University 



of Bon7i, Germa7iy.~\ 



[Translation. ] 



February 20, 1903. 

 I am so busy at the end of our semester that I can reply only 

 briefly to your letter of January 30. 



