180 



SCIENCE. 



[N. S. Vol. XII. No. 293. 



On the night before the eclipse each plate 

 had been carefully backed with a non- 

 halation solution consisting of caramel and 

 burnt sienna. The plates were at once 

 placed in the carrier ready for exposure. 



In preparing for the eclipse the question 

 of sensitiveness of the plates to be used 

 was carefully discussed with Professor Hale 

 and we finally decided to use the most sen- 

 sitive plates. The result justifies our de- 

 cision and shows that with a long focus in- 

 strument like this (y|-j) the plates cannot 

 be too sensitive. 



Two of the plates were Cramer double- 

 coated and were supposed not to be so sen- 

 sitive as the Cramer ' Crown.' Plate No. 

 1 (double-coated) was purposely left un- 

 backed. No. 7 was also double-coated and 

 backed. 



Up to this writing, plates No. 2, 5, 6 

 and 7 have been developed. They are re- 

 markably sharp and perfectly defined, and 

 show the prominences and inner corona 

 very beautifully. The polar fans come out 

 magnificently. There is a great deal of 

 beautiful detail in the inner corona that 

 promises to richly repay careful study. 



Great care is being exercised in the 

 development of the plates to insure not 

 only detail near the sun but to get also as 

 great extension as possible. 



Other instruments used were a 6-inch 

 and a 3i-inch portrait lens, mounted on 

 the equatorial mounting formerly owned 

 by Mr. Burnham and kindly loaned by 

 Professor Comstock. 



A 4J-inch Brashear portrait lens, and a 

 very sharp focus (1:1.9). Voightlander 

 lens of 4 inches aperture, were strapped to 

 a fixed post and were used for quick ex- 

 posures on the corona. Three Sonader 

 lenses, kindly loaned by Mr. Ellerman, 

 were placed on a small heliostat mounting 

 and were given an exposure extending 

 nearly through totality, with three differ- 

 ent kinds of plates. 



The plates with the small instrument 

 have, in part, been developed. The results 

 show an extension of the corona between 3 

 and 4 diameters of the moon. The corona, 

 as shown on these plates, is singularly like 

 that of January 1, 1889. There is a broad 

 fish-tailed extension spreading out to the 

 west more than half way to the planet Mer- 

 cury, which shows on all the plates. A long, 

 thick set, more or less pointed mass, extends 

 to the east for several diameters of the moon. 

 The poles are surmounted with fan -like 

 systems of rays — the whole entirely charac- 

 teristic of the sunspot minimum corona. 



The results with the ccelostat show that 

 it is by far the simplest and best instrument 

 for securing photographs of the corona on a 

 large scale. The results also show that the 

 images could be made very much longer 

 with much gain. An instrument of this kind 

 for photographing the corona could safely be 

 made several hundred feet in length with a 

 corresponding increase of aperture. 



G. A. Hill. A few remarks with regard 

 to the observations especially made to de- 

 termine the position of the moon. In 

 several of the reports the idea is presented 

 that the time predicted from the ephemeris 

 was not accurate. This I think was caused 

 by the position of the observer and his 

 station not being exactly known. At Law- 

 renceville we had a transit telescope, and 

 we computed the times of contact. The 

 times of the second and third contact agreed 

 within 0.5 second with the ephemeris, and 

 the times of the first and last contact came 

 within 1.9 second. The duration of the 

 totality was exactly given from the ephe- 

 meris. At Barnesville we had a clock giv- 

 ing seconds, with the 60th second left out, 

 and the gentleman who took the time there 

 lost his count, omitting that second, so that 

 we were a second late in our time. But 

 this was not the fault of the ephemeris, but 

 of the man who counted on the clock. I 

 was much gratified with the condition of the 



