But there is no _Ultima Thule_ in the progress of science. With the
recent augmentations of telescopic power, the details of the nebular
theory, proposed by Sir W. Herschell with such courage and ingenuity,
have been drawn in question. Many--most--of those milky patches in which
he beheld what he regarded as cosmical matter, as yet in an unformed
state,--the rudimental material of worlds not yet condensed,--have been
resolved into stars, as bright and distinct as any in the firmament.
I well recall the glow of satisfaction with which, on the 22d of
September, 1847, being then connected with the University at Cambridge,
I received a letter from the venerable director of the Observatory
there, beginning with these memorable words:--"You will rejoice with
me that the great nebula in Orion has yielded to the powers of our
incomparable telescope! * * * It should be borne in mind that this
nebula, and that of Andromeda [which has been also resolved at
Cambridge], are the last strongholds of the nebular theory."[A]
[Footnote A: _Annals of the Observatory of Harvard College_, p. 121.]
But if some of the adventurous speculations built by Sir William
Herschell on the bewildering revelations of his telescope have been
since questioned, the vast progress which has been made in sidereal
astronomy, to which, as I understand, the Dudley Observatory will be
particularly devoted, the discovery of the parallax of the fixed stars,
the investigation of the interior relations of binary and triple systems
of stars, the theories for the explanation of the extraordinary, not to
say fantastic, shapes discerned in some of the nebulous systems--whirls
and spirals radiating through spaces as vast as the orbit of Neptune;[A]
the glimpses at systems beyond that to which our sun belongs;--these are
all splendid results, which may fairly be attributed to the school of
Herschell, and will for ever insure no secondary place to that name in
the annals of science.
[Footnote A: See the remarkable memoir of Professor Alexander, "On the
origin of the forms and the present condition of some of the clusters of
stars, and several of the nebulæ," (Gould's _Astronomical Journal_, Vol.
iii, p. 95.)]