ON THE TOTAL ECLIPSE OF THE SUN, MAY 28, 1900. 
403 
Description of the Photographs. 
No. 1 (Plate 2), an exposure of about 5 seconds, commencing 10 seconds after the 
beginning of totality. 
The structure of the corona to a height of 5' of arc shows much fine detail, and, 
speaking generally, it is lower at the poles. Several prominences are shown on 
the east limb, but the most conspicuous are two bright ones in the south-west 
quadrant, which were of sufficient height to extend above the moon’s edge at this 
phase of the eclipse; the smaller prominences on the west were covered when the 
photograph was taken. 
From the south to the east point the moon’s limb is very jagged and rough, 
apparently caused by the chromospheric light being seen in the valleys of the Ptook 
Mountains in the south, and the Cordilleras and D’Alemherts towards tim east jDoint, 
which have an elevation of from 4 to 5 miles. There is also a rough surface at about 
the position of the Hercynian range, north of the east point, but it is not so well 
marked as in the case of the southern ranges. 
The chromosphere extending from a little nortli of east to slightly beyond the 
south pole has a well-defined serrated outer edge. This is mucli brighter than the 
adjacent corona. 
No. 2. An instantaneous exposure at about 18 seconds after the commencement 
of totality. 
The same remarks apply to this photograph. The corona is faintly visible, chiefly 
on the east and west limbs, where it extends only about 1’3 seconds of arc. The 
prominences differ from those in No. 1 in their great distinctness and in the slight 
variation produced by the change in the moon’s position. The corona fades off very 
gradually from the limb and shows some detail. 
No. 3 (Plate 3), an exposure of about 40 seconds, lasting until 5 seconds before 
the end of totality. This photograph is remarkable for the sharp outline of the moon, 
which must have moved neai'ly 18 seconds of arc (about -^th of an inch on the 
negative) during the taking of the plate. This effect is probably due to the rapidly 
increasing brightness of the lower part of the inner corona, so that the parts of the 
corona last uncovered on the retreating side of the moon, and those first covered by 
the advancing side, are strongly impressed, notwithstanding their relatively short 
exposures. 
The inner part of the corona is rather dense owing to the length of the exposure, 
but there is a good deal of detail in the higher parts, which can be well seen in the 
negative, but which can hardly be brought out in a reproduction. The prominences 
are clearly seen by making a small hole in a piece of black paper and placing it on 
the photograjrh, as suggested by Mr. Wesley when be examined these plates. 
The corona extends about 16 minutes of arc on the eastern side, and to a rather 
less degree, about 12 minutes, on the western side of the sun’s equator. 
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