The spiral nebula in the more northern of the Canes
Venatici was discovered by Messier on the 13th of Octo-
ber, 1773 (on the occasion of his discovery of the Comet), in
the left ear of Asterion, very near rj (Benetnasoh) in the tail
of the Great Bear (No. 51 of Messier, and No. 1622 of the
great Catalogue published in the Philos. Transact, for 1833,
p. 496, fig. 25). This is one of the most remarkable phenom-
ena in the firmament, both on account of its singular config-
uration, and of the unexpected transformative efiect produced
on its appearance by Lord Rosse's six-feet speculum. In Sir
John Herschel's eighteen-inch reflector, the nebula presented
the appearance of a spherical body, surrounded by a far-dis-
tant ring, so that it exhibited, as it were, an image of our
starry stratum with its galactic ring.f But in the spring of
1845, the large Parsonstown telescope transformed the whole
into a helicine twisted coil — a luminous spiral, whose convo-
lutions appear unequal, and are prolonged at both extremi-
ties, both in the center and outward, into dense, granular,
globular nodules. Dr. Nichol made a drawing of this object,
which was laid before the meeting of the British Association
at Cambridge in 1845 by Lord Rosse.} But the most per-

* Compare pi. ii., fig. 2, with pi. v. in Thoughts on some important
Paints relating to the System of the World, 18'16 (by Dr. Nichol, Pro-
fessor of Astronomy at Glasgow), p. 22. " Lord Rosse," says Sir John
Herschel, Outlines, p. 607, " describes and figures it as resolved into
numerous stars with much intermixed nebula."

t Cosmos, vol. i., p. 150, and note, where the nebula. No. 1622, is
lermed a " brother-system."

X Report of the Fifteenth Meeting of the British Association for tht
Advancement of Science, Notices, yy. 4; Nichol, Thoughts, Tp. 23. (Com-

fiare pi. ii., fig. 1, with pi. vi.) In the Outlines, § 882, we find the i()l-
owiug passage : " The whole, if not clearly resolved into stars, has a
resolvable character, which evidently indicates its composition."



MAGELLANIC CLOUDS. <13

feet delineation of this nebula has heen given by Mr. John-
stone Stoney. {Philos. Transact., 1850, pait i., pi. xxxv.,
fig. 1.) A similar spiral form is observed in No. 