deepen in color until it became a truly wonderful
object, its redness of hue irresistibly suggesting the idea that it was
something hot and glowing. During the following years it underwent
various changes of appearance, now fading almost to invisibility and now
brightening again, but without ever completely vanishing, and it is
still (1901) faintly visible.

Nobody has yet suggested an altogether probable and acceptable theory as
to its nature. Some have said that it might be a part of the red-hot
crust of the planet elevated above the level of the clouds; others that
its appearance might be due to the clearing off of the clouds above a
heated region of the globe beneath, rendering the latter visible through
the opening; others that it was perhaps a mass of smoke and vapor
ejected from a gigantic volcano, or from the vents covering a broad area
of volcanic action; others that it might be a vast incandescent slag
floating upon the molten globe of the planet and visible through, or
above, the enveloping clouds; and others have thought that it could be
nothing but a cloud among clouds, differing, for unknown reasons, in
composition and cohesion from its surroundings. All of these hypotheses
except the last imply the existence, just beneath the visible cloud
shell, of a more or less stable and continuous surface, either solid or
liquid.

When the red spot began to lose distinctness a kind of veil seemed to be
drawn over it, as if light clouds, floating at a superior elevation, had
drifted across it. At times it has been reduced in this manner to a
faint oval ring, the rim remaining visible after the central part has
faded from sight.

One of the most remarkable phenomena connected with the mysterious spot
is a great bend, or scallop, in the southern edge of the south belt
adjacent to the spot. This looks as if it were produced by the spot, or
by the same cause to which the spot owes its existence. If the spot were
an immense mountainous elevation, and the belt a current of liquid, or
of clouds, flowing past its base, one would expect to see some such bend
in the stream. The visual evidence that the belt is driven, or forced,
away from the neighborhood of the spot seems complete. The appearance of
repulsion between them is very striking, and even when the spot fades
nearly to invisibility the curve remains equally distinct, so that in
using a telescope too small to reveal the spot itself one may discover
its location by