many made the sign of the cross.

It was not long before Bailey's idea that the prominences were a part
of the corona was abandoned, and it was perceived that the two
phenomena were to a great extent independent. At the eclipse of 1868,
which the astronomers, aroused by the wonderful scene of 1842, and
eager to test the powers of the newly invented spectroscope, flocked
to India to witness, Janssen conceived the idea of employing the
spectroscope to render the prominences visible when there was no
eclipse. He succeeded the very next day, and these phenomena have been
studied in that way ever since.

There are recognized two kinds of prominences -- the ``erruptive'' and
the ``quiescent.'' The latter, which are cloud-like in form, may be
seen almost anywhere along the edge of the sun; but the former, which
often shoot up as if hurled from mighty volcanoes, appear to be
associated with sun-spots, and appear only above the zones where spots
abound. Either of them, when seen in projection against the brilliant
solar disk, appears white, not red, as against a background of sky.
The quiescent prominences, whose elevation is often from forty
thousand to sixty thousand miles, consist, as the spectroscope shows,
mainly of hydrogen and helium. The latter, it will be remembered, is
an element which was known to be in the sun many years before the
discovery that it also exists in small quantities on the earth. A fact
which may have a significance which we cannot at present see is that
the emanation from radium gradually and spontaneously changes into
helium, an alchemistical feat of nature that has opened many curious
vistas to speculative thinkers. The eruptive prominences, which do not
spread horizontally like the others, but ascend with marvelous
velocity to elevations of half a million miles or more, are apparently