98 Sir J. Herschel’s Astronomical Observations 
years, “the actual or smaller ellipse being curiously packed with- 
in the other, in the manner of an osculating curve, intersecting 
it in four points, and deviating from it in the intervals between 
them by a quantity much too small to excite any suspicion of 
error at that time.”” The period assigned by young Mason, (171 
years,) differs only 11 years from that now given by Sir John 
Herschel ; but the estimates of different astronomers have varied 
from 124 to 196; and Maedler (whose observations on this binary 
system are especially confided in) gives the period of 14878 
years. ‘Che mean of the results obtained by Herschel and Maed- 
ler is 165-5, differing only 54 years from the period assigned by 
Mason. 
The finest star of the southern hemisphere is Alpha Centauri. 
“This superb star, beyond all comparison the most striking ob- 
ject of the kind in the heavens, and to which the discovery of 
its parallax by the late Professor Henderson, has given a degree 
of astronomical importance no less conspicuous, consists of two in- 
dn wt both of a high ruddy or orange color, though that of the 
r is of a somewhat more sombre'and brownish cast. They 
pment together a star which to the naked eye is equal to or 
somewhat superior to Arcturus in Justre. In the 20 feet reflector 
it was ‘truly a noble object,’ its sam could be distinctly seen 
through good superfine drawing paper, and at four feet from the 
eye-piece, it showed on the paper sect in front (by ‘teflected not 
transmitted rays) a superb double star.” 
But our limits will not allow us to attempt a complete estiibis 
one = the astronomical riches of these comparatively unexplored 
reg We must content ourselves with a very brief notice of 
thei remeniaalh chapters. The third chapter treats of Astrometry, 
or the — — of the apparent magnitudes of the 
stars,—a subjec ich well deserves the attention of. practic 
astronomers, since ie want of a perfectly uniform and precise 
method of determining the comparative magnitudes of the stars, 
is universally acknowledged. But we are compelled to omit, a“ 
the present, any attempt to exhibit Sir John Herschel’s peculiar 
views in relation to this subject. 
Chapter fourth presents us with a most interesting view of the 
distribution of the stars in the southern hemisphere. It was no 
small object with Sir John Herschel to ascertain whether the 
views which his illustrious Father had originated respecting the 
constitution of the Galaxy, derived from observations on 
northern heavens, were corroborated by similar observations on ° 
the southern. It is well known that as early as_ 1785, Sir Wil- 
rschel announced, in the Philosophical Transactions, as 
the result of —— ‘‘ gauges” of the heavens, that the com- 
parative abunda scarcity of stars in any particular region 
of the northem hemisphere, and of the southern, so we — 
: 2a He es" 
