the sense that it is burning hot, which means
only that it will make any combustible substance burn which is brought
into contact with it), and it will not be consumed though the coal fire
be maintained around it for days and weeks and months. So with the
hydrogen flames which play at all times over the surface of our own sun.
They are not burning like the hydrogen flames which are used for the
oxy-hydrogen lantern. Were the solar hydrogen so burning, the sun would
quickly be extinguished. They are simply aglow with intensity of heat,
as a mass of red-hot iron is aglow; and, so long as the sun's energies
are maintained, the hydrogen around him will glow in this way without
being consumed. As the new fires of the star in the Crown died out
rapidly, it is possible that in their case there was actual combustion.
On the other hand, it is also possible, and perhaps on the whole more
probable, that the hydrogen surrounding the star was simply set glowing
with increased lustre owing to some cause not as yet ascertained.

Let us see how these two theories have been actually worded by the
students of science themselves who have maintained them.

'The sudden blazing forth of this star,' says Mr. Huggins, 'and then the
rapid fading away of its light, suggest the rather bold speculation that
in consequence of some great internal convulsion, a large volume of
hydrogen and other gases was evolved from it, the hydrogen, by its
combination with some other element,' in other words, by _burning_,
'giving out the light represented by the bright lines, and at the same
time heating to the point of vivid incandescence the solid matter of the
star's surface.' 'As the liberated hydrogen gas became exhausted' (I now
quote not Huggins's own words, but words describing his theory in a book
which he has edited) 'the flame gradually abated, and, with the
consequent cooling, the star's surface became less vivid, and the star
returned to its original condition.'

On the other hand, the German physicists, Meyer and Klein, consider the
sudden development of hydrogen, in quantities sufficient to explain such
an outburst, exceedingly unlikely. They have therefore adopted the
opinion, that the sudden blazing out of the star was occasioned by the
violent precipitation of some mighty mass, perhaps a planet, upon the
globe of that remote sun, 'by which the momentum of the falling mass
would be changed into molecular motion, or in other words into heat and