RESULTS OF OBSERVATIONS OF THE ECLIPSE BY 



THE EXPEDITION FROM THE YERKES 



OBSERVATORY. 



By EDWIN B. FROST. 

 (Read April ^5, J919.) 



The expedition from the Yerkes Observatory for the observa- 

 tion of the solar echpse of June 8, 1918, occupied three stations: 

 the principal one at Green River, Wyoming, the second at the 

 Chamberlin Observatory at the University of Denver, and (3) a 

 site near Matheson, Colorado, which had been selected by Professor 

 Barnard and the writer on a reconnaissance trip in 191 7. 



At the last-named station, Professor Edison Pettit, of Washburn 

 College, Topeka, Kansas, who was at the time an assistant at the 

 Yerkes Observatory, aided by ]\Iiss Hannah B. Steele, then fellow 

 in astronomy at the University of Chicago, and by others, obtained 

 some good photographs of the corona with the use of the twelve- 

 inch objective of Washburn College, stopped down to an aperture 

 of four inches, combined with a moving plate according to Schae- 

 berle's method. The first slide shows one of Mr. Pettit's best pic- 

 tures, with an exposure of one second. The weather was unfavor- 

 able in the weeks preceding the eclipse for a considerable extent of 

 the track of totality, but it fortunately cleared at IMatheson at the 

 time of the eclipse. Other parties which made successful observa- 

 tions at this station were that of Professor Loud and Mr. Hartley, 

 that from Drake University under Professor Morehouse, and that 

 from the University of Toronto under Professor Chant. 



At Denver we received the great courtesy from Director Howe 

 of the use of the twenty-inch Clark equatorial. A special auto- 

 collimating spectroscope with a Michelson plane grating belonging 

 to the Yerkes Observatory was adapted in our shops to fit the Den- 

 ver equatorial. Professor Schlesinger kindly loaned us an attach- 

 ment from the Porter spectrograph of the Allegheny Observatory 



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