nd
positive, no one would be entitled to set off against it, as of equal
weight, the merely negative evidence of some one or two deposits of the
carboniferous age that did not bear the carboniferous character, even
were such known to exist; far less is anyone entitled to set off against
it the _possibly_ negative evidence of deposits of the carboniferous age
not yet discovered nor examined; for that would be simply to set off
against good positive evidence, what is no evidence at all. It would be
to set off the _possible_ evidence of the absent witnesses, not yet
precognosced in the case, against the express declarations of the
witnesses already examined, and strong on the positive side.

Surely an American, before appealing, in a question of this kind, to the
bare possibility of the existence somewhere or other of barely negative
evidence, ought to have bethought him of the very extraordinary positive
evidence furnished by the carboniferous deposits of his own great
country. The coal fields of Britain and the European continent had been
wrought for ages ere those of North America were known, and for ages
more after it had been but ascertained that the New, like the Old World,
has its Coal Measures. And during the latter period the _argument_ of
Mr. Foulke might have been employed, just as now, and some member of a
learned society might have urged that, though the coal fields of Europe
bore evidence to the former existence of a singularly luxuriant flora,
beyond comparison more vast than the European one of the present day,
the same could not be predicated of the American coal fields, whose
carbonized remains _might_ be found representative of a flora which had
been at least not more largely developed than that existing American
flora to which the great western forests belong. Now, however, the time
for any such argument has gone by; the American coal fields have been
carefully explored; and what is the result? The geologist has come to
know, that even the mighty forests of America are inconsiderable,
compared with its deposits of coal; nay, that all its forests gathered
into one heap would fail to furnish the materials of a single coal seam
equal to that of Pittsburg; and that centuries after all its thick woods
shall have disappeared before the axe, and it shall have come to present
the comparatively bare, unwooded aspect of the long civilized countries
of Southern Europe, it will continue to derive the elements of its