THE SPROUL OBSERVATORY ECLIPSE EXPEDITION, 



JUNE 8, 1918. 

 Coronal Arches and Streamers. 



By JOHN A. MILLER. 



(Read April 25, 1919.') 



The Eclipse expedition from Sproul Observatory was located at 

 Brandon, Colo., a station on the Missouri Pacific, approximately 

 fifty miles from the Colorado-Kansas line. 



This region is very dry, and the weather conditions are favor- 

 able. During the month preceding the eclipse the sun was either 

 clear or only thinly clouded, at 5 : 26 P.M. on all but six days ; and 

 in general the afternoons were better than the forenoons. The 

 wind was usually high, often very high, and the air many times was 

 full of dust. It was so cloudy all day on June 5, 6 and 7, and the 

 forenoon of June 8, that at no time could successful observations 

 have been made. This was the longest period of cloudy weather 

 that we had while there. At noon of June 8, however, it cleared, 

 and at the time of totality only two small clouds were visible west 

 of the meridian, one about twenty degree above the sun and the 

 other near the horizon. The seeing was fairly steady. 



The following instruments were mounted : 



I. One lens, nine inch aperture, focal length 62^/2 feet. This 

 was mounted as the Lick Observers since 1893 have mounted their 

 long focus lenses. Exposures of two seconds, twenty seconds, 

 forty-five seconds, and three seconds were made with this lens. 



II. On a polar axis, two lenses of four inches and three and one 

 half inches aperture, respectively, and of focal length eleven feet 

 two inches were mounted. The exposure with each of these lenses 

 was for eighty-two seconds. 



III. In another polar axis were mounted six lenses varying in 

 focal length from ten and one half to fifty inches ; also a transmis- 

 sion grating. 



IV. A three-prism slit spectrograph with which we hoped to 



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