On the Corona of the Sun. 



115 



The total solar eclipse of May 6, 1883, furnished an opportunity of 

 comparing the photographs taken with an eclipsed sun with those 

 taken in this country without an eclipse. On the day of the eclipse 

 the weather was bad here, but plates taken before and after the 

 eclipse were placed in the hands of Mr. Wesley, who had had much 

 experience in making drawings from photographs taken during former 

 eclipses. Mr. Wesley drew from .these plates before any information 

 reached this country of the results obtained at Caroline Island ; he 

 was, therefore, wholly without bias in the drawings which he made 

 from them. When these drawings were compared afterwards with 

 the Caroline Island plates, the general resemblance of the corona was 

 strong, and the iden tity of the object photographed in England and 

 at Caroline Island seemed placed beyond doubt by a remarkably 

 formed rift on the east of the north pole of the sun, which is seen 

 very nearly in the same position in the English plates and in those 

 taken during the eclipse. This rift, slightly modified in form, was 

 found to be present in a plate taken about ,a solar rotation-period 

 before the eclipse, and also on a plate taken about the same time after 

 the eclipse.* 



In 1884, a grant from the fund placed annually by the Government 

 at the disposal of the Royal Society was put into the hands of a 

 committee appointed by the Council of the Royal Society for the pur- 

 pose of photographing the corona at a place of considerable elevation. 

 The Committee selected the Eiffel, near Zermatt, which has an eleva- 

 tion of 8,500 feet, and appointed as photographer Mr. Ray Woods, 

 who, as assistant to Professor Schuster, had photographed the corona 

 during the eclipse of 1882, and who in conjunction with Mr. Lawrance 

 had photographed the eclipse of the following year at Caroline 

 Island. 



Unfortunately during this year a very large amount of scattered 

 light was always present about the sun, arising, it would seem, from 



* Eeport B. Ass. Advanc. Science, 1883, p. 348, and Plates XI and XIa. 



It seems desirable to put on record here a letter written by Mr. Lawrance to 

 Professor Stokes, dated September 14, 1883 " Dr. Huggins called upon Mr. Woods 

 this morning and showed us the drawings Mr. Wesley has made of his coronas. He 

 told us that he particularly did not wish to see our negatives, but that he would like 

 us to compare his results with ours. We did*so, and found that «ome of the strongly 

 marked details could be made out on his drawings, a rift near the north pole being 

 especially noticeable ; this was in a photograph taken on April 3, in which the detail 

 of the northern hemisphere is best shown, while the detail of our southern hemi- 

 sphere most resembles the photograph taken on June 6 ; in fact, our negatives seem 

 to hold an intermediate position. Afterwards I went with Dr. Huggins and 

 Mr. Woods to Burlington House to see the negatives. The outline and distribution 

 of light in the inner corona of April 3 is very similar to that on our plate which 

 had the shortest exposure ; the outer corona is, however, I think, hidden by atmo- 

 spheric glare. As a result of the comparison I should say that Dr. Huggins' 

 coronas are certainlv genuine as far as 8' from the limb." 



I 2 



