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III. lotal Eclipse of the Sun ohserved at Caroline Island, on 6th May, 1883. 
By Cap)tain W. de W. Abney, C.B., E.E., F.R.S. 
Received May 25,—Read Jane 16, 1887. 
Revised June 4, 1888. 
[Plates 1, 2.] 
Owing to the representations of the Committee on Solar Physics, who communicated 
with the Royal Society the desirability of observing this eclipse, an expedition was 
organised under the auspices of the latter body. The Council of the Royal Society 
having requested me to draw up a report on the Total Eclipse observed at Caroline 
Island, I undertook the task so far as relates to the results which were obtained with 
the same instruments which were employed in the observations of the Total Eclipse 
in Egypt in 1882. 
Two observers, Mr. IT. Lawrance and Mr. C. R. Woods, who had both taken 
part in the Eclipse Expedition to Egypt as assistants to Professors Lockyer and 
Schuster, were entrusted with the arduous duty of making the observations. The 
expedition was devoted entirely to photographic work, the main object being to continue 
the photographic observations which had been carried on in Egypt, consisting of photo¬ 
graphs of the corona taken on very rapid plates with varying exposure, photographs 
of the corona taken with a slitless spectroscope (the prismatic camera), and a 
photograph of the corona spectrum, the image of the moon and the corona being 
thrown on the slit cutting the diameter of the former. There is no occasion to describe 
the instruments which were employed for the first two classes of observations, as they 
have been fully described in the previous communication to the Royal Society by 
Professor Schuster and myself which appears in the ‘Philosophical Transactions’ for 
1884. The photographic spectroscope which was employed on this occasion differed in 
one detail, and in one detail only, in that the dispersion was doubled, two medium dense 
flint prisms of 62^° being employed instead of one prism of the same angle. The expe¬ 
rience gained in Egypt seemed to show that, if the coronal light was equally bright in the 
two eclipses, the rapid plates used on both occasions would be amply adequate to secure 
photographs with the larger dispersion. Besides these observations several others were 
made, but did not meet with the success it was hoped they would have done. A photo¬ 
heliograph, giving a 4-inch solar image, was attached to an equatorial mount, in addition 
to the wooden camera carrying a lens of 5 ft. 6 in. focus, with which the smaller-sized 
pictures of the corona were taken in Egypt. The pictures taken with the former, 
13.4.89 
