THE APPEARANCE OF THE CORONA. 93 



was divided into four parts by two chalk lines crossing at right 

 angles at the centre of the moon-circle. [No such divisions 

 were shown in the copy.] Mrs. Oakes always took the top right- 

 hand quadrant, Mrs. Bevan the top left-hand ; Mr. Nicolson the 

 bottom right-hand quadrant, Mr. Moore the bottom left-hand. 

 After 5 seconds' warning the copy was exposed, the counting 

 began, and each drew his own quadrant until at 90 seconds 

 the copy was withdrawn. All the drawings were then collected 

 on to one paper, by being copied, and the result was critically 

 compared with the original. The original was then rotated, 

 and suspended by another side, so that each observer had a 

 fresh quadrant to draw. After four drawings each observer thus 

 had a complete corona drawn by himself; and there were also 

 four combined drawings in which the errors of one observer 

 were partially annulled by the work of the others. It soon 

 appeared that the observers had a "personal equation," and 

 that while some were always too timid, others were always too 

 bold, etc. But after a few nights of steady practice all drew 

 closely together, nervousness disappeared, and the combined 

 results became excellent. All measurements and comparisons 

 were invariably made in terms of the diameter of the eclipsing 

 moon. 



On eclipse-day the danger was, of course, the fatigue to the 

 <-\ v induced by succumbing to the temptation to look too often 

 at the sun during partial eclipse, either through smoked glass 

 or through some of the excellent telescopes. (The Rev. Septimus 

 Hebert's capital instrument proved an especial snare in this 

 respect.) The director of the section was perhaps over-eager in 

 guarding his flock. For a few minutes before the eclipse 

 became total the whole four sat in position (as arranged at 

 rehearsal on the previous day) perfectly prepared, with plumb- 

 lines adjusted in front of their chairs, etc., but with closed eyes ; 

 and they did not look up until by the beginning of the count ing 

 they knew that the corona was visible. In spite of all these 

 precautions it was found that one of the party had used his eyes 

 too freely beforehand, and his quadrant suffered thereby, but 

 the practices had been of such service that the observers of the 

 adjoining quadrants were able to supplement the deficiency, 

 having had time to go beyond the borders of their own simpler 

 quadrants. The knowledge that Venus was 12 diameters away 

 afforded an invaluable measure. 



The whole of the afternoon was spent in making a most 

 careful combined drawing; other observers kindly aiding the 

 section with criticism, which was freely welcomed. The result, 

 when agreed upon, was at once photographed for greater security, 

 as well as the separate drawings. Unhappily the plate had 

 already served ! Such accidents will occur. The original chalk 

 drawings, however, although of such fugitive material, were 



