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MR. J. N. LOCKTBR AND DR. SCHUSTER ON 
can only be made with instruments constructed for the purpose. We feel sure that if 
in future expeditions an instrument similar to that used by Mr. Janssen is provided, 
the spectrum of the corona can be photographed. As far as the higher regions are 
concerned, it is true we shall not learn anything beyond what is given by the prismatic 
camera, but as far as the lower regions are concerned important results may be 
expected. 
VIII. PHOTOGRAPHS AND SKETCHES OF THE CORONA. 
We must inquire next what information was obtained from the photographs and 
sketches of the corona itself. Eight photographs were obtained by means of a small 
camera belonging to Mr. Beasley, the object glass having a focal length of about 13 
inches. The camera was not moved by clockwork, but during the short exposure the 
sun’s movement, though visible, does not materially affect the results. The times of 
exposure were 2, 4, 8, and 16 seconds, and two photographs of each exposure were 
obtained. As these two sets show exactly the same phenomena we need only 
consider one set, remembering, however, that the other set excludes the possibility of 
any of the results being affected by irregularities in the collodion-film. The four 
photographs are shown in figs. 10, 11, 12, and 13. 
Looking over one set we are first struck by the rapid increase in the extent of the 
corona through an increase in the time of exposure ; the last of the photographs, 
having been exposed 16 seconds, shows an extent exceeding the diameter of the sun. 
The next point of interest is the symmetry of the outer corona round the sun’s axis. 
This symmetry was dwelt on by Mr. E. J. Stone, in the eclipse of April, 1874. 
(Memoirs of Royal Ast. Soc., vol. xlii. p. 31.) 
The small size of our photographs does not, indeed, allow us to fix the position of 
the axis within one or two degrees, but even then, allowing for this uncertainty, the 
symmetry is very striking. We have marked, as well as could be ascertained, the 
position of the sun’s axis on fig. 7, Plate 9. The similarity in the corona, as observed 
by us and by Mr. Stone just one year before, is exceedingly curious. The drawings 
given by Mr. Stone, in so far as they agree amongst themselves, agree with the corona 
observed at Siam. This similarity does not merely extend to the symmetry about the 
sun’s axis, but also to the irregularities in this symmetry. Thus the nearly straight 
boundary lines of the corona, which cut the axis at nearly right angles, are not quite 
parallel but converge in both eclipses towards the east. The west side of the corona 
seems much more compact, the east side broken up into what the Siamese called fish- 
tails. The similarity is, perhaps, most striking between Mr. Bright’s drawing 
(L. C., p. 51) of the corona in 1874, and the drawing made by Prince Tong (fig. 14, 
Plate 13), by order of His Majesty the King of Siam, of the corona in 1875. The two 
drawings could certainly pass for representations of one and the same eclipse. 
At the observatory the Honorable H. N. Shore undertook to sketch the corona. 
