ox THE TOTAL SOLAR ECLIPSE OF AUGUST 29, 1886. 
311 
The instantaneous photographs of the corona were complete blanks, proving, 1 
think, that the exposure had been far too short. I developed them with the same 
solutions, and for at least the same length of time, as when developing, immediately 
beforehand, some of the plates exposed during the partial eclipse ; the instrument was 
in the same condition as before and after totality, when successful photographs were 
taken. These circumstances are worth mentioning, to show that I did not fall into 
some of the commoner traps with which the photographer is surrounded. Three of 
the photographs showed signs of fog, which was probably only due to the length of 
time which I allowed them to stay in the developer. 
The long exposure photographs were not taken with any special object beyond that 
of obtaining a record of the corona. The plates used were bromo-gelatine dry plates 
prepared by Captain Abney, and I used the ordinary alkaline development. The 
extension of the corona shown on these plates is not very great, and they show signs 
of vibration; they have, however, I hope, been of use to Mr. Wesley in his drawing 
of the inner parts of the corona. As my main object was to get instantaneous 
photographs, these plates had to be taken without removing the automatic shutter; 
the shutter had, therefore, to be worked by hand, and this probably caused the vibra¬ 
tion. It may, however, have been caused by a puff of wind ; and on another occasion 
I should take far greater precautions against this danger by surrounding myself with 
canvas screens in all exposed directions, and as high as possible. 
6. Comments and Conclusions. 
Returning again to the consideration of my observations with regard to the special 
uses of the coronagraph, it will be seen that my results are adverse to the possibility 
of obtaining photographs of the corona during Sun light with this instrument. It is, 
however, I consider, by no means proved that the method is impossible, for there are 
several reasons why this trial should not be considered conclusive. 
(1.) The atmospheric conditions were very unfavourable. The air was fully charged 
with moisture, and on the morning of the eclipse the sky was certainly not of that 
dark blue which, no doubt, indicated atmospheric purity. It was slightly hazy, and 
not, I think, as clear as an average English blue sky. About a minute after totality 
I noticed a halo with prismatic colours round the Sun—an indication, I presume, of 
suspended matter. 
(2.) The Sun was at a low elevation during the eclipse, and the station was only 
about a couple of hundred feet above the sea. Both these circumstances, no doubt, 
increased the air glare. 
(3.) Professor Thorpe’s observations at this eclipse show that the light from the 
corona was not so bright as on other occasions. This also appears to be the general 
impression amongst other observers who had seen previous eclipses. If this was due 
to the corona not being so luminous, the opportunity was, no doubt, an unfavourable 
one independently of the state of the atmosphere. But this effect is not to be 
