ound the sun in
an eclipse when the moon has completely covered the last remaining
crescent of the sun. A general idea of the appearance of the corona is
given in Fig. 20, and we further present in Plate V. the drawing of the
corona made by Professor Harkness from a comparison of a large number of
photographs obtained at different places in the United States during the
total eclipse of July 29th, 1878. In Fig. 21 we are permitted by the
kindness of Mr. and Mrs. Maunder to reproduce the remarkable photograph
of the corona which they obtained in India during the eclipse of January
22nd, 1898.

[Illustration: Fig. 21.--View of Corona during the Eclipse of Jan. 22nd,
1898 (_Reproduced by kind permission of Mr. and Mrs. Maunder and of the
proprietors of "Knowledge._")]

The part of the corona nearest the sun is very bright, though not so
brilliant as the prominences, which (as Professor Young says) blaze
through it like carbuncles. This inner portion is generally of fairly
regular outline, forming a white ring about a tenth part of the solar
diameter in width. The outer parts of the corona are usually very
irregular and very extensive. They are often interrupted by narrow
"rifts," or narrow dark bands, which reach from the limb of the sun
through the entire corona. On the other hand, there are also sometimes
narrow bright streamers, inclined at various angles to the limb of the
sun and not seldom curved. In the eclipses of 1867, 1878, and 1889, all
of which occurred at periods of sun-spot minimum, the corona showed long
and faint streamers nearly in the direction of the sun's equator, and
short but distinct brushes of light near the poles. In the eclipses of
1870, 1882, and 1893, near sun-spot maxima, the corona was more
regularly circular, and chiefly developed over the spot zones. We have
here another proof (if one were necessary) of the intimate connection
between the periodicity of the spots and the development of all other
solar phenomena.

In the spectrum of the corona there is a mysterious line in the green,
as to the origin of which nothing is at present certainly known. It is
best seen during eclipses occurring near the time of sun-spot maximum.
It is presented in the ordinary solar spectrum as a very thin, dark
line, which generally remains undisturbed even when lines of hydrogen
and other substances are twisted and distorted by the violent rush of
disturbed elements. The line is always present among the bright