with great rapidity, and such loudness that they
were heard all over a circle about sixty leagues in
diameter. They appeared to come from a brilliant
cloud. An emission of a vapour resembling smoke
followed each explosion. This was at mid-day, in
an almost cloudless sky, and immediately after
the first explosion, and during the whole time
they lasted, an immense number of aërolites fell
to the ground with a hissing noise. Nearly three
thousand of these were afterwards picked up,
the largest of which weighed over seventeen
pounds.

It is not possible to give a positive answer to
the question: Why is the fall of an aërolite always
preceded by an explosion? Generally
there is a single explosion, but this is not invariably
the case, as we have just mentioned one
instance in which there was a succession. Almost
simultaneously with the report, the aërolite
strikes the earth. Whenever this has occurred
in the presence of a spectator, it has always been
found that the stone was exceedingly hot. The
mass of meteoric iron which was dug out of the
ground at a village in the Punjaub, was almost
too hot to be touched, though it had penetrated
to a considerable depth in the earth, and some
time must have elapsed between its fall and
the arrival of the officer of the district on the
spot. This mass was sent to the emperor, who
directed it to be made into a sabre, knife, and
dagger. Heat was likewise very sensible in the
case of the stone which fell at Ensisheim on the
7th of November, 1492, though it had to be dug
out of the earth from a depth of between five and
six feet. This stone was placed in the church
at that place by order of the Emperor Maximilian,
where it may still be seen; the French,
who carried it off to Paris during the Revolution,
having subsequently returned it to the place
whence they had taken it, minus a fragment
retained for the museum of the Jardin des Plantes.
One tremendous explosion was said to have
accompanied the fall of this meteoric stone, and the
same was the case with that, weighing fifty-six
pounds, which fell near Captain Topham's
house in Yorkshire, descending perpendicularly
to the earth, and burying itself in the chalk
beneath the surface soil. I can myself vouch
for one instance where, at the conclusion of
the most terrific thunder-storm I ever witnessed,
a tremendous explosion was accompanied by
the fall of a number of fragments of an
aërolite within a few yards of the house in
which I was sitting. Some of these I kept in my
possession.

One of the objections formerly urged against
the assertion that these meteoric stones fell from
the atmosphere, was the fact that they were
sometimes found on the surface of the earth. Pallas
describes an immense mass of meteoric iron he
met with on a slate mountain in Siberia, and few
of the thousands who have visited the British
Museum can have failed to notice a mass of a
similar kind lying on the floor in the mineral
department, which, though it weighs over
fourteen hundred pounds, is not a tithe of that
from which it was separated, and which is
still lying on the plain of Otumba, in Buenos
Ayres.

That these aërolites do as a rule penetrate the
earth, we have now ample evidence, and there
may be special reasons why in the cases just
mentioned such enormous masses did penetrate so
slightly. I suppose that the larger the mass of
meteoric iron, the softer it will be when it comes
in contact with the earth; moreover, the force
of the collision will be affected by the height at
which the explosion takes place. That these
masses really fell from the atmosphere, I believe
nobody competent to speak on the subject will
now attempt to deny; there is the indisputable
evidence of identity of composition between
them and those aërolites which have fallen in
the presence of witnesses. Nowhere in mines
has iron ever been discovered in a pure state,
but only in the condition of ore. Aërolites are
chiefly composed of pure iron, to which are
added in small, but slightly varying proportions,
nickel, cobalt, sulphur, zinc, silica, and magnesia.

How far this uniformity of constitution may
be affected, or produced by fusion in the
atmosphere, and the probable presence of electricity
drawn up with the vapours about the equator
to descend again at the pole, we do not know
that they become incandescent in passing
through our atmosphere, we have seen in
hundreds of instances quite recently, and the
explanation of this is given by the rapidity with
which they traverse it, varying according to
estimation, from eighteen to forty miles a second.
The lowest of these rates would be sufficient to
raise the temperature of the mass to a degree
we can hardly realise. This exceeding vividness
to a certain extent accounts for the different
versions that are given of the apparent size of
the remarkable fire-ball, seen on the night of the
4th of last March: the eyes of different individuals
not being affected alike by strongly
luminous objects. This most remarkable meteor
was visible over the greater part of England, as
well as on the Continent. Dr. Heis, of the Royal
Academy of Munster, has given a complete
description of it; and, as he is a professor of
astronomy, it may be inferred that his account is
less likely to be exaggerated than that of an
unscientific observer. He says that in a clear
bright sky, every object near him was suddenly
lighted up by a fire-ball, apparently about the size
of the moon when at the full. The time during
which it was visible, he estimates at from three
to six seconds, the speed at which it moved at
forty-seven miles a second, and its actual diameter
nearly fourteen hundred feet. Its brilliancy
remarkably dazzling, and its motion attended
with a hissing noise. Thus it may be
inferred that the professor is not far wrong in
his estimate, that it approached within seventeen
miles of the earth, and that its volume was as
enormous as he computes it. The long trail of