time, is to be ultimately
abolished by the agency which produced it. In the words of our authors,
"If the visible universe be developed from an invisible which is not
a perfect fluid, then the argument deduced by Sir William Thomson
in favour of the eternity of ordinary matter disappears, since this
eternity depends upon the perfect fluidity of the invisible. In fine,
if we suppose the material universe to be composed of a series of
vortex-rings developed from an invisible universe which is not a perfect
fluid, it will be ephemeral, just as the smoke-ring which we develop
from air, or that which we develop from water, is ephemeral, the only
difference being in duration, these lasting only for a few seconds,
and the others it may be for billions of years." Thus, as our authors
suppose that "the available energy of the visible universe will
ultimately be appropriated by the invisible," they go on to imagine,
"at least as a possibility, that the separate existence of the visible
universe will share the same fate, so that we shall have no huge,
useless, inert mass existing in after ages to remind the passer-by of
a form of energy and a species of matter that is long since out of date
and functionally effete. Why should not the universe bury its dead out
of sight?"

In one respect perhaps no more stupendous subject of contemplation than
this has ever been offered to the mind of man. In comparison with the
length of time thus required to efface the tiny individual atom, the
entire cosmical career of our solar system, or even that of the whole
starry galaxy, shrinks into utter nothingness. Whether we shall adopt
the conclusion suggested must depend on the extent of our speculative
audacity. We have seen wherein its probability consists, but in
reasoning upon such a scale we may fitly be cautious and modest in
accepting inferences, and our authors, we may be sure, would be the
first to recommend such modesty and caution. Even at the dimensions to
which our theorizing has here grown, we may for instance discern the
possible alternative of a simultaneous or rhythmically successive
generation and destruction of vortex-atoms which would go far to modify
the conclusion just suggested. But here we must pause for a moment,
reserving for a second paper the weightier thoughts as to futurity
which our authors have sought to enwrap in these sublime physical
speculations.

PART SECOND.

UP to this point, however remote from ordi