more above the surface of the sphere. The appearance of this
shining field, which is called the corona, reminds one of the aurora
which glows in the region about either pole of the earth.

One of the first results of the invention of the telescope was the
revelation of the curious dark objects on the sun's disk, known by the
name of spots from the time of their discovery, or, at least, from the
time when it was clearly perceived that they were not planets, but
really on the solar body. The interest in the constitution of the
sphere has increased during the last fifty years. This interest has
rapidly grown until at the present time a vast body of learning has
been gathered for the solution of the many problems concerning the
centre of our system. As yet there is great divergence in the views of
astronomers as to the interpretation of their observations, but
certain points of great general interest have been tolerably well
determined. These may be briefly set forth by an account of what would
meet the eye if an observer were able to pass from the surface of the
earth to the central part of the sun.

[Illustration: _Lava stream, in Hawaiian Islands, flowing into the
sea. Note the "ropy" character of the half-frozen rock on the sides of
the nearest rivulet of the lava._]

In passing from the earth to a point about a quarter of a million
miles from the sun's surface--a distance about that of the moon from
our sphere--the observer would traverse the uniformly empty spaces of
the heavens, where, but for the rare chance of a passing meteorite or
comet, there would be nothing that we term matter. Arriving at a point
some two or three hundred thousand miles from the body of the sun, he
would enter the realm of the corona; here he would find scattered
particles of matter, the bits so far apart that there would perhaps be
not more than one or two in the cubic mile; yet, as they would glow
intensely in the central light, they would be sufficient to give the
illumination which is visible in an eclipse. These particles are most
likely driven up from the sun by some electrical action, and are
constantly in motion, much as are the streamers of the aurora.

Below the corona and sharply separated from it the observer finds
another body of very dense vapour, which is termed the chromosphere,
and which has been regarded as the atmosphere of the sun. This layer
is probably several thousand miles thick. From the manner in which it
moves,