ors; a proof, surely, not only of the vast amount of the vegetation
in the coal-making age, but also of the vast time during which it
lasted. The Lepidodendra may have been fifty or sixty feet high.
There is not a Lycopodium in the world now, I believe, five feet
high. But the club-mosses are now, in these islands and elsewhere,
lovers of wet and peaty soils, and so may their huger prototypes have
been, in the old forests of the coal.

Of the Sigillariae we cannot say as much with certainty, for
botanists are not agreed as to what low order of flowerless plants
they belong. But that they rooted in clay beds there is proof, as
you will hear presently.

And as to the Conifers, or pine-like trees--the Dadoxylon, of which
the pith goes by the name of Sternbergia, and the uncertain tree
which furnishes in some coal-measures bushels of a seed connected
with that of the yew--we may suppose that they would find no more
difficulty in growing in swamps than the cypress, which forms so
large a portion of the vegetation in the swamps of the Southern
United States.

I have given you these hints, because you will naturally wish to know
what sort of a world it was in which all these strange plants grew
and turned into coal.

My answer is, that it was most probably just like the world in which
we are living now, with the one exception that the plants and animals
are different.

It was the fashion a few years since to explain the coal--like other
phenomena of geology--by some mere hypothesis of a state of things
quite unlike what we see now. We were brought up to believe that in
the Carboniferous, or coal-bearing era, the atmosphere was intensely
moist and hot, and overcharged with carbonic acid, which had been
poured out from the interior of the planet by volcanic eruptions, or
by some other convulsion. I forget most of it now: and really there
is no need to remember; for it is all, I verily believe, a dream--an
attempt to explain the unknown not by the known, but by the still
more unknown. You may find such theories lingering still in
sensational school-books, if you like to be unscientific. If you
like, on the other hand, to be scientific you will listen to those
who tell you that instead of there having been one unique
carboniferous epoch, with a peculiar coal-making climate, all epochs
are carboniferous if they get the chance; that coal is of every age,
from that of the Scotch and E