258 
CAPTAIN W. DE W. ABNEY AND DR. A. SCHUSTER 
of the other observers within hearing of my signals as to their accuracy. Mr. Baillie, 
who had joined the expedition, and to whose excellent sketch of the corona we shall 
have occasion to refer, wrote directly after the eclipse as follows : “ I was seated at my 
table just before totality, and, being unable to look upwards, kept my eye on the watch 
in my hand, waiting for Schuster’s signal. Immediately upon hearing his voice I 
looked up at the sun. Totality was complete.” 
Mr. Lawrance, Mr. Lockyer’s assistant, who was looking through Mr. Lockyer’s 
finder, writes as follows : “ The moment Dr. Schuster gave his signal of commence¬ 
ment of totality, I still saw Bailey’s beads and a thin crescent of the sun still un¬ 
covered. I think, however, that totality commenced within a second or two.” 
It appears from Mr. Lawuiance’s statement that my signal could not have been 
given too late, while the photographs give conclusive proof that I could not have been 
too early by any appreciable amount. For as I called out I drew the slide of the 
spectroscopic camera, and Mr. Woods, on hearing me give the signal, removed the 
cap from the prismatic camera. The plate in this camera would have been spoiled had 
any sunlight been allowed to fall on it. I may have been a little late at the end of 
totality, as Mr. Baillie remarks, but when a signal is given by calling out, a good 
fraction of a second must necessarily intervene between the time that a phenomenon 
is seen and the time that the signal is actually given and realised by another observer. 
On the whole, it may be said that the calculated time of totality was as nearly realised 
as possible. 
Part II.—(Drawn up by Captain Abney and Dr. Schuster.) 
Y .—The photographs of the corona. 
Across all the photographs of the corona is a transparent line, which is the shadow 
of a platinum wire stretched immediately in front of the slide placed there to enable 
us to fix, with accuracy, the position of the corona. Before and after totality the 
clockwork of the telescope was stopped, and the solar cusps were photographed at 
fixed intervals. The position of the platinum wire could thus be referred to the 
line of the sun’s motion. On a paper print of these photographs the position of the 
centres of the solar images was determined as accurately as possible, and it was found 
that a line joining these centres made an angle of about 45 minutes with the image 
of the platinum wire. Thanks to the courtesy of Mr. Whipple, we had an opportunity 
of measuring our photographs with Mr. De la Hue’s instrument, which is now deposited 
at Kew. The photographs taken previous to totality showed a sufficient part of the 
sun uncovered to enable us to draw a tangent, and thus to determine with great 
accuracy the direction of the sun’s motion. This method gave an angle of 49 minutes 
between the wire and the circle of declination, a result practically identical with that 
previously obtained. The angle between the lines joining the cusps and the wire are 
slightly different, but this is due to the moon’s motion over the solar disc. Owing to 
