composed largely of metallic vapors -- i.e. metals which are usually
solid on the earth, but which at solar temperatures are kept in a
volatilized state. The velocity of their ascent occasionally amounts
to three hundred or four hundred miles per second. It is known from
mathematical considerations that the gravitation of the sun would not
be able to bring back any body that started from its surface with a
velocity exceeding three hundred and eighty-three miles per second; so
it is evident that some of the matter hurled forth in eruptive
prominences may escape from solar control and go speeding out into
space, cooling and condensing into solid masses. There seems to be no
reason why some of the projectiles from the sun might not reach the
planets. Here, then, we have on a relatively small scale, explosions
recalling those which it has been imagined may be the originating
cause of some of the sudden phenomena of the stellar heavens.

Of the sun-spots it is not our intention here specifically to speak,
but they evidently have an intimate connection with eruptive
prominences, as well as some relation, not yet fully understood, with
the corona. Of the real cause of sun-spots we know virtually nothing,
but recent studies by Professor Hale and others have revealed a
strange state of things in the clouds of metallic vapors floating
above them and their surroundings. Evidences of a cyclonic tendency
have been found, and Professor Hale has proved that sun-spots are
strong magnetic fields, and consist of columns of ionized vapors
rotating in opposite directions in the two hemispheres. A fact which
may have the greatest significance is that titanium and vanadium have
been found both in sun-spots and in the remarkable variable Mira Ceti,
a star which every eleven months, or thereabout, flames up with great
brilliancy and then sinks back to invisibility with the naked eye. It
has been suggested that sun-spots are indications of the beginning of