The Total Solar Eclipse of 1900. 69 
very well defined, and there are clear indications of the interesting arching struc- 
tures of the corona about the great prominences in the west and south-west. A 
small portion of the reappearing Sun (or very bright chromosphere) on the west 
is sharply reversed, but has scarcely had any effect in fogging the plate. The 
prominences are finely shown, and are more distinct than in Plate A. 
Both negatives are somewhat marred by a shift of the plate, producing a 
second image of the brighter portions, but they are otherwise very clear and free 
from defects. The polar diameter of the Moon’s image is 53 mm. (= 2:1 in.): the 
equatorial diameter is slightly less, owing to the motion of the Moon during 
exposure. 
The corona of 1900 belongs to the type which appears to have always accom- 
panied a minimum Sun-spot period, though not so markedly as in 1878, and 
January, 1889. 
_ The polar rifts are widely opened and filled with the fine rays so generally 
seen in these regions at minimum periods. They are far finer and more delicate 
about the north pole than at the south, where they are more diffused and 
indistinct. 
With regard to the main equatorial masses of the corona, the edges bounding 
the western side of the north and south polar rifts are much less inclined from 
the radial in an equatorial region than the corresponding edges on the eastern 
side. The corona therefore is more spreading on the west and more pointed on 
the east, producing the general resemblance to the form of a wind vane that has 
been so often noted. This is of course best shown on Plate vi, with the longer 
exposure: this plate also shows the characteristic curve of double curvature of 
the edge bounding the north polar rift to the west. There are clear indications 
of interlacing or arching structure in the corona on the west side, in the region 
of the large prominences, in contrast with the more uniform and quiescent 
appearance of the eastern side, where the prominences are smaller and less 
conspicuous. 
The prominences are well shown on both plates, the larger being on the west 
or south-west. One of these forms a kind of arch, as though two adjacent promi- 
nences were united by a band across their summits. 
Remarks on the Reproductions. 
Owing to the difficulty of reproducing the prominences and coronal extensions 
on the same plate, two plates have been made from negative B—the photograph 
taken towards the conclusion of totality with an exposure of about 19 secs. 
Plate vi. gives a good general idea of the photograph; and the structure of the 
