SOME RECENT CONTRIBUTIONS TO OUR KNOWLEDGE 



OF THE SUN ^ 



By GEORGE E. HALE, Sc. D., LL.D. 



Director oi' Solar Observatory oe Carnegie Institution of Washington, 

 AT Mount Wilson, California 



With Thirteen Plates 



Mr. Secretary, Ladies and Gentlemen : When I was honored 

 by an invitation to deHver the Hamilton Lecture, and to describe in it 

 some of our recent solar investigations, I accepted with special pleas- 

 ure, since it would afford me a fitting opportunity to acknowledge 

 the important debt owed by the Mount Wilson Solar Observatory 

 to the Smithsonian Institution. Soon after the Carnegie Institution 

 of Washington was organized, Doctor Walcott, then Secretary of its 

 Executive Committee, requested Secretary Langley, of the Smith- 

 sonian Institution, to express an opinion as to the advisability of es- 

 tablishing a solar observatory at some mountain station. Doctor 

 Langley, who knew, from personal experience at Mount Whitney 

 and other elevated points, the importance of conducting solar re- 

 search above the denser and more disturbed portions of the atmos- 

 phere, strongly recommended to the Carnegie Institution that pro- 

 vision be made for the proposed observatory. In the subsequent 

 consideration of this project by the Executive Committee, Doctor 

 Walcott gave it his full support, and thus contributed in an important 

 way toward the favorable decision finally reached. It is therefore 

 easy to understand why we of the Solar Observatory owe a debt of 

 gratitude to these Secretaries of the Smithsonian Institution. I beg 

 to assure Doctor Walcott that his interest in our work is most 

 heartily appreciated. 



When one pauses to reflect that the United States possesses more 

 astronomical observatories than any other nation, and that it is un- 

 surpassed in its contributions to astronomical discovery, one may 

 naturally ask why it seemed advisable to establish another new ob- 

 servatory. If it were a question of duplicating existing instruments, 

 or of entering fields of research already well occupied, it is probable 



* Lecture delivered at Washington, D. C, April 22, 1908, under the auspices 

 of the Hamilton Fund of the Smithsonian Institution. 



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