A Popular History of Astronomy During the Nineteenth Century: Fourth EditionClerke, Agnes M. (Agnes Mary)
History
A Popular History of Astronomy During the Nineteenth Century: Fourth Edition
Clerke, Agnes M. (Agnes Mary)
Astronomy -- History -- 19th century
The splendour of the celestial objects as viewed with this vast
"light-grasper" surpassed all expectation. "Never in my life," exclaimed
Sir James South, "did I see such glorious sidereal pictures."[327] The
orb of Jupiter produced an effect compared to that of the introduction
of a coach-lamp into the telescope;[328] and certain star-clusters
exhibited an appearance (we again quote Sir James South) "such as man
before had never seen, and which for its magnificence baffles all
description." But it was in the examination of the nebulæ that the
superiority of the new instrument was most strikingly displayed. A large
number of these misty objects, which the utmost powers of Herschel's
specula had failed to resolve into stars, yielded at once to the
Parsonstown reflector; while many others showed under entirely changed
forms through the disclosure of previously unseen details of structure.
One extremely curious result of the increase of light was the abolition
of any sharp distinction between the two classes of "annular" and
"planetary" nebulæ. Up to that time, only four ring-shaped systems--two
in the northern and two in the southern hemisphere--were known to
astronomers; they were now reinforced by five of the planetary kind, the
discs of which were observed to be centrally perforated; while the
definite margins visible in weaker instruments were replaced by ragged
edges or filamentous fringes.
Still more striking was the discovery of an entirely new and most
remarkable species of nebulæ. These were termed "spiral," from the more
or less regular convolutions, resembling the whorls of a shell, in which
the matter composing them appeared to be distributed. The first and most
conspicuous specimen of this class was met with in April, 1845; it is
situated in Canes Venatici, close to the tail of the Great Bear, and
wore, in Sir J. Herschel's instruments, the aspect of a split ring
encompassing a bright nucleus, thus presenting, as he supposed, a
complete analogue to the system of the Milky Way. In the Rosse mirror it
shone out as a vast whirlpool of light--a stupendous witness to the
presence of cosmical activities on the grandest scale, yet regulated by
laws as to the nature of which we are profoundly ignorant. Professor
Stephen Alexander of New Jersey, however, concluded, from an
investigation (necessarily founded on highly precarious data) of the
mechanical condition of these extraordinary agglomerations, that we see
in them "the partially scattered fragments of enormous masses once
rotating in a state of dynamical equilibrium." He further suggested
"that the separation of these fragments may still be in progress,"[329]
and traced back their origin to the disruption, through its own
continually accelerated rotation, of a "primitive spheroid" of
inconceivably vast dimensions. Such also, it was added (the curvilinear
form of certain outliers of the Milky Way giving evidence of a spiral
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