(284.) 
New Se- 
condary 
Planets. 
Mr Lassell, 
(285.) 
His instru- 
ments, 
860 
20 Massilia 1852 Sept.19 De Gasparis. 
21 Lutetia Noy. 15 Goldschmidt. 
22 Calliope Nov. 16 Hind. 
23 Thalia Dee. 15 Hind. 
24 Themis 1853 April 5 De Gasparis. 
25 Phocewa April 6 Chacornac, 
26 Proserpine May 5 Luther. 
27 Euterpe Nov. 8 Hind. 
28 Bellona 1854 March 1 Luther. 
29 Amphitrite March 1 Marth. 
30 Urania July 22 Hind. 
31 Buphrosyne Sept. 1 Ferguson. 
32 Pomona Oct, 26 Goldschmidt. 
33 Polyhymnia Oct. 28 - Chacornac. 
34 Circe 1855 April 6 Chacornac. 
35 Leucothea April 19 Luther. 
Mr Lassett.— New Secondary Planets—Mr Las- 
sell of Liverpool deserves a more lengthened no- 
tice than our limits will permit, not only as a dis- 
tinguished discoverer, but as one whose success can- 
not be too widely made known as an encouragement 
to others. This gentleman, engaged in mercantile 
pursuits in an eminently commercial town, possessing 
little leisure and no enormous fortune, has contrived, 
in the intervals of business, to construct with his own 
hands telescopes which in accuracy of definition ap- 
pear to rival any which art stimulated by national 
liberality has yet constructed elsewhere, and to use 
them with a degree of skill and success which has 
not been exceeded (nor in some respects equalled) 
by any astronomer whether professional or otherwise. 
I speak, let it be observed, of accuracy of definition, 
such as is necessary to display minute points of 
light, like the satellites of Uranus. In respect of 
the amount of illumination requisite for the display 
of many diffuse faint objects among the nebula, the 
gigantic telescopes of Herschel and Lord Rosse are 
of course superior. 
Mr Lassel’s observatory near Liverpool was erected 
in 1840. The principal instrument is a reflecting 
telescope of 24 inches aperture (completed, however, 
only some years later), mounted equatoreally, an ar- 
. Tangement requiring great mechanical skill, but, as 
the results show, most effectually accomplished. The 
speculum was worked and polished by machinery con- 
structed by Mr Nasmyth, but principally devised by 
Mr Lassell, after he had examined and tried Lord 
Rosse’s method. I should think it must be admitted 
to be the most perfect optical work of its kind ever 
made: for I believe there is no test object in existence 
which Mr Lassell has not seen with it; in fact he 
has discovered the most delicate tests himself,—the 
6th star of the group @ Orionis (though not /irst seen 
MATHEMATICAL AND PHYSICAL SCIENCE. 
(Diss. VI. 
by him), a satellite of Neptune, an eighth satellite of 
Saturn, and several satellites of Uranus. 
Not many days had elapsed after the discovery of 
Neptune, before Mr Lassell, directing his telescope 
to it, perceived a satellite (as he believed) on Oct. 
10, 1846. The discovery was fully made out in the 
following year, and was soon after verified by the 
great refractors of Pulkowa and Western Cambridge 
(U.S.) Its period is about 5-879 days,! and its dis- 
covery was of singular importance as leading to a 
knowledge of the mass of the planet. 
Till 1848 only seven satellites of Saturn were ad- 
mitted. The two closest to the planet were detected 
by Sir William Herschel in 1789, and have been 
seen by very few astronomers since. During five 
years’ residence at the Cape, Sir John Herschel never 
but once obtained even a doubtful glimpse of the 
closest with an 18-inch mirror. The third, fourth, 
and fifth were discovered by Cassini in 1684; the 
sixth and most conspicuous by Huygens in 1654: the 
outermost by Cassini in 1671. ‘To these an eighth 
satellite, intermediate in position between the two 
last, was added by Mr Lassell on the 19th September 
1848. By a singular coincidence, it was recognised 
as a satellite the very same evening by Mr Bond of 
Cambridge (in America) with the great Munich re- 
fractor. The new body was called Hyperion, in con- 
formity with Sir John Herschel’s suggestion of distin- 
guishing the satellites as well as the planets by mytho- 
logical names. On the 22d November 1850 Mr Las- 
sell saw at once Saturn with his whole train of eight 
satellites—a glorious spectacle probably enjoyed byno 
other astronomer, In the same month of November 
Mr Bond discovered a faint or dusky ring of Saturn 
interior to the two long known. It is probably ne- 
bulous, for by Mr Lassell’s observations and Mr 
Jacob’s it appears to be transparent. 
Sir William Herschel thought that he recognised 
six satellites of Uranus. The second and fourth of 
his table have been observed by several astronomers, 
particularly Sir John Herschel and M. Lamont. 
Their periods are 84 174 and 134114, To these Mr 
Lassell, aided by the fine climate of Malta (to which 
for two seasons he removed his telescope), has con- 
clusively added two more: one, appearing to coin- 
cide with the closest of Herschel’s, of which the 
period is 44 35 28™, and one still nearer the planet 
revolving in 24 12™ 29s, the shortest orbital revolu- 
tion in the solar system. Mr Lassell doubts se- 
riously the existence of any other satellite.” 
1 From Mr Lassell’s observations at Malta, 1852-3, 
2 See Astron. Society’s Notices, xiii, 151; and xiv. 133. 
(286.), 
He disco- 
vers a Sa- 
tellite of 
Neptune, 
(287.) - 
and one of 
Saturn. 
Faint ring 
of Saturn 
discovered 
by Mr > © 
Bond. 
(288.) 
Satellites » 
of Uranus. 
