earth would be nearly a
month's journey from the point indicated!

It is, indeed, very difficult to say what form of damage the earth
would suffer from such a collision. In 1861 it passed, as we have seen,
through the tail of the comet without any noticeable result. But the
head of a comet, on the other hand, may, for aught we know, contain
within it elements of peril for us. A collision with this part might,
for instance, result in a violent bombardment of meteors. But these
meteors could not be bodies of any great size, for the masses of comets
are so very minute that one can hardly suppose them to contain any large
or dense constituent portions.

The danger, however, from a comet's head might after all be a danger to
our atmosphere. It might precipitate, into the air, gases which would
asphyxiate us or cause a general conflagration. It is scarcely necessary
to point out that dire results would follow upon any interference with
the balance of our atmosphere. For instance, the well-known French
astronomer, M. Camille Flammarion,[39] has imagined the absorption of
the nitrogen of the air in this way; and has gone on to picture men and
animals reduced to breathing only oxygen, first becoming excited, then
mad, and finally ending in a perfect saturnalia of delirium.

Lastly, though we have no proof that stars eventually become dark and
cold, for human time has so far been all too short to give us even the
smallest evidence as to whether heat and light are diminishing in our
own sun, yet it seems natural to suppose that such bodies must at last
cease their functions, like everything else which we know of. We may,
therefore, reasonably presume that there are dark bodies scattered in
the depths of space. We have, indeed, a suspicion of at least one,
though perhaps it partakes rather of a planetary nature, namely, that
"dark" body which continually eclipses Algol, and so causes the
temporary diminution of its light. As the sun rushes towards the
constellation of Lyra such an extinguished sun may chance to find itself
in his path; just as a derelict hulk may loom up out of the darkness
right beneath the bows of a vessel sailing the great ocean.

Unfortunately a collision between the sun and a body of this kind could
not occur with such merciful suddenness. A tedious warning of its
approach would be given from that region of the heavens whither our
system is known to be tending. As the dark object would become visible
only