tion,
in general, being at variance with the idea of revolution about a common
centre.

"It is difficult," says Sir John Herschell, "to form any conception of
the dynamical state of such systems. On one hand, without a rotary
motion and a centrifugal force, it is hardly possible not to regard them
as in a state of _progressive collapse_. On the other, granting such a
motion and such a force, we find it no less difficult to reconcile their
forms with the rotation of the whole system [meaning cluster] around any
single axis, without which internal collision would appear to be
inevitable."

Some remarks lately made about the "nebulae" by Dr. Nichol, in taking
quite a different view of the cosmical conditions from any taken in this
Discourse--have a very peculiar applicability to the point now at issue.
He says:

"When our greatest telescopes are brought to bear upon them, we find
that those which were thought to be irregular, are not so; they approach
nearer to a globe. Here is one that looked oval; but Lord Rosse's
telescope brought it into a circle.... Now there occurs a very
remarkable circumstance in reference to these comparatively sweeping
circular masses of nebulae. We find they are not entirely circular, but
the reverse; and that all around them, on every side, there are volumes
of stars, _stretching out apparently as if they were rushing towards a
great central mass in consequence of the action of some great
power_."[12]

[12] I must be understood as denying, _especially_, only the
_revolutionary_ portion of Maedler's hypothesis. Of course, if
no great central orb exists _now_ in our cluster, such will
exist hereafter. Whenever existing, it will be merely the
_nucleus_ of the consolidation.

Were I to describe, in my own words, what must necessarily be the
existing condition of each nebula on the hypothesis that all matter is,
as I suggest, now returning to its original Unity, I should simply be
going over, nearly verbatim, the language here employed by Dr. Nichol,
without the faintest suspicion of that stupendous truth which is the key
to these nebular phaenomena.

And here let me fortify my position still farther, by the voice of a
greater than Maedler--of one, moreover, to whom all the data of Maedler
have long been familiar things, carefully and thoroughly considered.
Referring to the elaborate calculations of Argelander--the very
researches which form Maedler's basis--_Humboldt_,