256 
CAPTAIN W. DE W. ABNEY AND DR, A. SCHUSTER 
had a sensitiveness for the blue end of the spectrum between fifty and sixty times 
greater than an ordinary wet plate. This is a matter of no slight importance when it 
is remembered that in comparison with photographic observations made during all 
other eclipses, except, perhaps, that of 1878, this exquisite sensitiveness has in effect 
turned seconds of time into minutes, thus enabling much more to be done in a short 
totality than could be accomplished in a much longer one when using the older 
process. 
III .—The totality. 
During the present short eclipse it was of special importance that the signal at the 
beginning of totality should be correctly given. If given too early, the plates would 
be spoiled by the presence of the last gleam of the sun, while if too late valuable 
time would be lost, and there would be the danger of exposing the plates beyond the 
end of totality, and thus again destroying their value. Experience during the last 
two eclipses had taught me that the corona was distinctly visible four or five 
seconds before totality, and I therefore determined on giving three signals : the first 
when the rapidly waning crescent showed that the critical moment was approaching; 
the second when I could see the corona against the dark limb of the moon ; and finally 
when totality had set in. Mr. Buchanan undertook to measure the interval between 
the two last signals. In order to make sure that all the lenses were covered at 
the end of totality, it was decided to utilise only 65 seconds out of the 70 we hoped to 
have. Proceedings during totality were carried out strictly according to the pro¬ 
gramme laid down. My time and attention were so much occupied in looking after 
the slides and cameras that I had only a few seconds to spare for eye-observations, and 
no value can be attached to impressions gained in so short a time. I did not, indeed, 
notice any striking difference in the appearance in this and the two previous eclipses, 
except the presence of the prominences which I now saw for the first time, and which 
seemed to colour the greater part of the inner corona with a tint which appeared to me 
to be much more of a light orange than of a red colour. The photographs show, how¬ 
ever, a very considerable difference between the outline and distribution of the corona 
in this and the three last eclipses. In the short time at my disposal I did not notice 
the comet, to which reference will be made, though it was very conspicuous to the 
majority of the party. 
IV. — Time observations. 
It was not part of the regular programme of the expedition to take any regular 
time observations, and the following results have therefore little value, except, perhaps, 
so far as the duration of totality is concerned. 
The longitude and latitude of the place of observation was determined by M. 
Trepied : the former by means of four lunar culminations, the latter by means of a 
