two types have been
always distinct; they are different races, who have no common
origin." But if you found, as you will find, many types of man
showing endless gradations between the white man and the Negro, and
not only that, but endless gradations between them both and a third
type, whose extreme perhaps is the Chinese--endless gradations, I
say, showing every conceivable shade of resemblance or difference,
till you often cannot say to what type a given individual belongs;
and all of them, however different from each other, more like each
other than they are like any other creature upon earth; then you are
justified in saying, "All these are mere varieties of one kind.
However distinct they are now, they were probably like each other at
first, and therefore all probably had a common origin." That seems
to me sound reasoning, and advanced natural science is corroborating
it more and more daily.

Now apply the same reasoning to coal. You may find about the world--
you may see even in England alone--every gradation between coal and
growing forest. You may see the forest growing in its bed of
vegetable mould; you may see the forest dead and converted into peat,
with stems and roots in it; that, again, into sunken forests, like
those to be seen below high-water mark on many coasts of this island.
You find gradations between them and beds of lignite, or wood coal;
then gradations between lignite and common or bituminous coal; and
then gradations between common coal and culm, or anthracite, such as
is found in South Wales. Have you not a right to say, "These are all
but varieties of the same kind of thing--namely, vegetable matter?
They have a common origin--namely, woody fibre. And coal, or rather
culm, is the last link in a series of transformations from growing
vegetation?"

This is our first theory. Let us try to verify it, as scientific men
are in the habit of doing, by saying, If that be true, then something
else is likely to be true too.

If coal has all been vegetable soil, then it is likely that some of
it has not been quite converted into shapeless coal. It is likely
that there will be vegetable fibre still to be seen here and there;
perhaps leaves, perhaps even stems of trees, as in a peat bog. Let
us look for them.

You will not need to look far. The coal, and the sands and shales
which accompany the coal, are so full of plant-remains, that three
hundred spec