Anniversary Address. XXV. 
` ECLIPSE. 
The total eclipse of the sun, visible throughout this part of the 
world, which took place on the 6th of May last, had been looked forward 
to by men of science with special attention, on account of the interest- 
ing questions which it was expected to solve. 
The roseate protuberances of the chromosphere which are seen 
surrounding the limb of the sun during an eclipse were, by the 
investigations which were made during and consequent upon the 
eclipse of 1868, proved to be jets, composed almost exclusively of 
incandescent hydrogen gas, to which I before referred in speaking 
of the passage of the comet, bursting forth from the layers of vapour 
which form the atmosphere to the sun. Amongst these vapours 
spectrum analysis has detected sodium, magnesium, and calcium. 
Beyond this atmosphere, however, there is visible during a total 
eclipse a magnificent silvery aureole, or luminous corona, which may 
reach to a distance equal to an entire radius of the moon's orbit. It 
is not yet certain of what this corona is composed, and it is quite 
possible that it may be a magnetic phenomenon analogous to the 
aurora borealis. The remarkable association of the breaking-out of 
sun-spots with the occurrence of violent magnetic storms on the sun's 
surface gives support to this view. A marked instance of this 
occurred on the 19th November last, when telegraphic communica- 
tion was interfered with throughout the world, and an aurora was visible 
over both hemispheres, associated with a very large sun-spot. 
To the corona again immense appendices have been observed. 
Whether they are dependent on the coronal atmosphere, or are really 
streams of meteorites circulating round the sun, was still uncertain ; 
and this was one of the questions which it was hoped would be 
decided by the observations taken during the eclipse of 1883, 
especially as bearing on the remarkable theory lately put forth by Dr. 
Siemens to explain the maintenance of the sun’s energy, which sug- 
gests that energy thrown off from the equatorial regions of the sun is 
reabsorbed at the sun’s poles, to be again re-formed into a source 
of power. p. 
From the observations of the eclipse it was moreover expected that 
information would be furnished respecting the small round spots which 
have frequently been observed to appear and disappear in front of the 
sun’s orb. Can these be planets, revolving round the sun, but which 
the illumination of our atmosphere, so bright in the neighbourhood 
of the sun, conceals from us at other times? There are but two ways 
in which the matter can be investigated— viz., the attentive study of 
the solar surface (a work of great difficulty), and the examination 
of the circumsolar region whilst an eclipse renders such examination 
possible. As ordinary eclipses have only a duration of two minutes 
