The Total Solar Eclipse of 1900. 67 
Instruments. 
As Sir Howard Grubb gives a detailed account of the instruments in a 
subsequent part of this Report, it is only necessary for me to state that they 
consisted of — 
(1) A ceelostat and photographic camera, fitted with a corrected lens of 4 in. 
aperture and of 19 ft. 4 in. focal length, for photographing the corona ; 
(2) A ccelostat and photographic camera, with a lens of 6 in. aperture and 
7 ft. 103 in. focal length, for photographing the corona through a 
coloured screen ; 
(3) A spectroscopic apparatus, for securing a continuous series of photographs 
of the ‘‘ flash spectrum.” 
Members of the Expedition. 
The following accompanied the expedition :— 
Pror. Cuarues J. Jory, M.A., F.T.C.D. (Chairman of the Committee). 
Sir Howarp Gruss, F.R.S. 
Dr. A. A. Rampaut, F.R.S. 
Mr. W. E. Witson, F.R.S. 
Pror. Brrain, M.A. 
Mr. Samuet Grocueecan, C.E. 
We met Mr. Rudolf Grubb at Plasencia, and were joined on the 27th by Dr. 
Downing, F.R.S., the Superintendent of the Nautical Almanac Office, who kindly 
gave the signal Start at the commencement of totality, and the signal Close cameras 
85 secs. after. The second signal was actually given some seconds after the end 
of totality, as the duration of the eclipse was less than its predicted extent, being 
only 82 secs. according to Dr. Downing’s observations. During totality the 
seconds were counted by Mr. Rudolf Grubb, using a metronome. Prof. Bergin 
assisted me in the adjustments of the long-focus camera, and uncapped for the 
exposures. Mr. Wilson manipulated the camera with the coloured screen, and 
Sir Howard Grubb and Dr. Rambaut worked the spectroscope. Dr. Downing and 
Mr. Geoghegan observed the shadow-bands. 
A preliminary account of the results of the expedition was presented to a 
jomt meeting of the Royal Dublin Society and the Royal Irish Academy, held 
on April 4th, 1901. 
Long-focus Camera. 
The adjustments of the ccelostat call for no special remarks, as the subject 
is treated at great length in most of the recent reports of expeditions fitted out 
N 2 
