TOTAL ECLIPSE OF THE SUN, JANUARY 22, 1898. 
1G7 
Lockyer’s preliminary report,^'" the green coronal image depicted by the prismatic 
cameras corresponds very closely with the image of the inner corona. 
Discs. 
The arrangement introduced by Professor Newcomb in 1878, in which a circular 
disc is used to protect the eye from the glare of the inner corona, was adopted to 
facilitate the search for faint extensions of the corona. 
The six discs were manned by eighteen volunteers. Of each party of three, one 
was pointer, one was observer, and the third the writer. A convenient seat being 
arranged for the observer from which he could comfortably get the disc and sun in 
line through his eyepiece, he made way for the pointer, who kept the eyepiece in 
line with disc and sun until the last moment. 
On the “ Alert ” being sounded at ten minutes before totality, the observer was 
blindfolded, and the bandage was only taken off 10 seconds after totality commenced. 
He then dictated what he saw, taking the most delicate and faintest effects first, and 
afterwards going round the moon’s disc clockwise to ensure nothing was omitted. 
After the eclipse was over, the observers, with the aid of the notes, made a sketch 
from memory. 
The observers had been selected from volunteers, and had been trained from the 
5th of January, a period of seventeen days. The method of selection and training 
was to show on the screen a slide of a corona from a previous eclipse, and allow 
duration of totality for copying it, and a few minutes after the slide had been 
removed for touching up from memory. 
Lieutenant Quayle, who adjusted the discs, reports as follows :—• 
“ The discs varied in size from G to 2 inches, and were made of thin wood, painted 
a dead black. Six discs were used, placed at from 40 to 15 feet from the eye, and 
covering from 7 to 3 minutes of arc. 
“ As the altitude of the sun at the time of eclip.se reached 53°, some difficulty 
was at first experienced in finding a suitable site so as to give the necessary 
elevation, hut eventually the inner wall of the fort was selected, and out of a varied 
collection ol' spars, uprights were chosen ; these were either driven into crevices in 
the wall, or fixed with staples and lashed. 
“ The correct position of each disc was obtained by means of a sextant, prismatic 
compass, and a measuring taj)e. 
“ The eyepieces were suspended on cross-bars, lashed between two u})rights about 
3 feet apart, thus giving a considerable horizontal motion, the eyepieces themselves 
supplying the correction for altitude. Lieutenant Colbeck assisted in erecting the 
disas.” 
In order to simplify the orientation, the vertex or “ top ” of the sun was to be 
‘ Roy. Soc. Proc.,’ vol. 64, p. 40. 
