guard another time, and not to be caught in the
same way again.

The position of space which immediately
surrounds the Sun is very imperfectly known to
men of science. The intensity of the light is
an insurmountable obstacle to close examination.
Eclipses, by extinguishing the light, allow
a temporary peep to be taken at these
unknown regions. Laplace's theory of the
constitution of the universe, combined with
the researches of modern astronomers, render
it probable that that dazzling belt conceals
many phenouema of which we are ignorant;
such as swarms of small planets, zones of
cosmic matter, as well as an enormous
atmosphere enveloping the Sun. Consequently it
has been asked whether the immense flame-like
tongues of light suddenly seen surrounding
the Moon's disc during the darkest moments of
an eclipse, be not really clouds, appendages, or
protuberances, belonging to the solar
atmosphere. At present, nothing is known with
certainty.

In 1860, we had another total eclipse of the
Sun, visible in Spain. That time, people were
not taken by surprise; the red protuberances
flaring round the lunar disc were duly
examined; but the uncertainty as to their real
nature was not removed. They certainly are
not mountain peaks, as some observers thought.
If several of the protuberances were pointed
and upright, a still larger number were rounded,
extending in length rather than in height.
Many seemed quite detached from the Sun,
resembling the cumulus clouds of our
atmosphere. Others, after rising perpendicularly,
were deflected laterally, like flames drawn on
one side by a current of air.

Some dozen years ago, Herschell's and
Arago's hypothesis respecting the constitution
of the Sun, was accepted by the world without
demur. The Sun (probably inhabited, according
to them) was enclosed within three distinct
enveloping atmospheres. The first, reckoning
from the Sun's surface, was thick and dense,
serving as a non-conducting screen, and also as
a highly efficient reflector. The second, above
it, was luminous and hot—a photosphere of
phosphorescent clouds. The third, overlying
the other two, consisted of a sort of external
gaseous atmosphere. These atmospheres had
independent movements and currents, by which
the spots on the Sun were explained. The
thickness of the two lower atmospheres
immediately enveloping the solid nucleus of the
Sun—itself quite moderate in temperature—
was estimated at a thousand leagues, or two
thousand five hundred English miles.

Besides its complexity, this theory involves
several insurmountable difficulties. What could
be the source of heat in the light-and-warmth-
giving atmosphere? We can conceive no
substance, liquid, or gas, capable of producing
such effects during a long lapse of ages.
William Herschell supposed it to be neither a liquid
nor an elastic fluid, but a stratum of phosphoric
clouds floating in the Sun's transparent
atmosphere. Again: What medium, interposed
between it and the Sun, could isolate and protect
the latter, sufficiently to make its surface habitable?
The progress of science has broken up
this curious nest of antagonistic boxes, one
acting as a heater the other as a cooler. The
triple scaffolding has given way. Nobody now
asks for cartes de visite of the Sun's inhabitants,
or feels uneasy about their weight in
consequence of the immense force of gravity
there. If an ox, there, be twenty-eight times
as heavy as with us, and the butchers' profits
in proportion; if a man, falling a distance
equal to his own height, would be as completely
smashed as if he jumped from the Monument;
if the Sun's inhabitants, as we have been
gravely assured, must be small slight creatures,
of a peculiarly elastic and supple organisation,
something like Sylphs in the Rape of the Lock;
it is all one to us, now o'days. The Sun's
inhabitants have vanished in smoke.

The present belief is that the Sun is simply
a body which is luminous in consequence of
high temperature pervading its whole
substance. Matter in fusion, obeying dynamical
laws, boils and heaves with ascending and
descending currents, which cause the appearances
known as spots in the Sun. The "protuberances,"
it is conjectured, are incandescent
vapours rising to the very confines of the solar
atmosphere.

As the heat and light given out by the Sun
cannot be maintained by ordinary combustion
—the Sun's whole mass would have been
burnt up long ago, were it made of any
earthly combustible—the most recent hypothesis
is, that its heat is caused by the arrested motion
of meteorites, planets, or other cosmic matter
falling into it. This is known as "The Meteoric
Theory of the Sun," and was propounded by
Mayer in 1848, and worked out fully. Dr.
Tyndall accepts it as very probable, if not
completely demonstrated, adding, " It would be a
great mistake to regard it as chimerical. It is
a noble speculation; and depend upon it, the
true theory, if this, or some form of it, be not
the true one, will not appear less wild or less
astounding."

We are better armed for observation in 1868
than in 1860. Spectral analysis* has furnished
us with a potent instrument capable of rendering
marvellous service. We now compel light
—the only link, besides gravity, which connects
us, with other worlds floating in open space—
to betray its secrets and tell us what it is
made of. Every luminous ray which reaches
us, can be forced to state its origin: whether
sent forth by a solid, or a gas: whether it
comes to us directly or by reflection. Thus,
the light proceeding from the protuberances,
submitted to spectral analysis, will inform us
whether those protuberances are solid;
whether they are clouds of solid particles or of
incandescent vapours; whether they shine with
their own proper light, or are merely bright

* See PHOTOLOGICAL FACTS, vol. xiii. p. 151.