ON THE TOTAL ECLIPSE OF THE SUN, MAY 28, 1900. 
401 
Part IIL—Photographs of the Corona taken with a 4-inch Cooke Lens of 
16 FEET FOCAL LENGTH. By HoWARD PaYN. 
The Camera. 
The instniment I used during the eclipse was a telescope fitted with a camera for 
taking pictures of the corona. The lens was a Cooke photovisual objective (Taylor’s 
Patent) of 4 inches aperture and 16 feet focal length, the sun’s image being there¬ 
fore If- inches in diameter. The fittings of the telescope were specially drawn 
for me by Mr. George Scorer, Architect, of Newman Street, and gave every 
satisfaction. 
The object glass was fitted in a mahogany box, the wood being 1 inch thick; this 
in its turn slid in and out of a holder of the same thickness; the camera at the 
other end was similarly fitted. 
Between the two ends were two sets of battens, each 8 feet long, supported in 
the centre by a scjuare wooden frame into which the battens screwed. The screws 
worked in 2-inch slots, so that by loosening the thumb screws at either end room 
was alForded for any shrinkage or expansion of any part of the instrument. 
The telescope when put together was supported on three solid piers, the two on 
which the ends rested being of brick. The whole was perfectly steady, even with a 
strong breeze blowing. 
The battens were covered in with brown pajier pasted round them, and outside this 
was a covering of tai;red paper. The covering on the whole was fairly light-tight, 
but the paper was veiy easily torn, especially when the telescojie was covered up at 
night with sails from the ship. During this operation the wind would flap parts of 
the sail against the tube, in spite of every care, and the paper was often broken. 
This could be repaired by pasting on fresh paper, but it was always a source of 
anxiety, and had any tearing of the paper happened during the exposures, the plates 
would probably have been spoilt. 
1 think that it would be better on another occasion to cover the battens with black 
cloth, with a mackintosh cover to fasten securely over that. The only covering 
then required at night would be for the object-glass and camera. This would save a 
good deal of trouble, and woidd much facilitate working the instruments at night, as, 
after the bluejackets have returned to the ship, it is often very difficult to open out 
coverings single-handed, especially in the dark. 
The focus was obtained by sliding the object-glass box in and out of the holder. 
The focus was tested by exposing plates on the sun and by photographing star trails. 
Mawson’s Castle plates were used, size 10 X 10, F No. 56, relative speed 1'5 
(Wynne’s exjiosure-meter scale.) 
3 F 
VOL. CXCVIII.—A. 
