SCIENTIFIC SUMMARY. 
265 
calculation, in at least two stars, Sirius and Procyon. In respect to the 
former star, Peters in 1851 found that the irregularities in its position 
could he explained by the motion of the bright star about an invisible one, 
the latter being in uniform motion. 
In respect to Procyon, Bessel’s hypothesis has also been confirmed, and 
a binary system in which Procyon moves about a dark star in an orbit 
whose plane is that of the visible heavens, the distance between the com- 
ponents being about a second and a quarter. The actual distance of 
Procyon from the Sun being approximately known, M. Auwers concludes 
that the mass of the dark body is about one-lialf of that of the Sun, and in 
any case the mass of the dark body must be at least a hundred times as 
great as that of Jupiter. If Procyon and its companion have equal masses, 
that of each would be greater than T y Tr ths of the Sun ; and if the mass of 
Procyon is equal to that of the Sun, that of its companion must be greater 
than 9i%ths that of the Sun. 
Mars. — By observations made at the Oxford Observatory between 
September 18 and October 26 of the present year, Mr. Main has determined 
the ratio of the polar to the equatorial diameters of Mars as 38 to 39, being 
almost exactly the same as found by Arago, and which has been so much 
doubted. On September 30, the ellipticity was found as 245 to 244, and 
on October 17, as 29 to 28, which are the extremes. For the equatorial 
diameter at the unit of the distance, Mr. Main finds giving a real 
diameter to the planet of 4,332 miles. 
Comet II. of 1862. — This comet was observed at Hobart Town until 
September 21, with the naked eye, at which time, of course, it was not at 
all visible in the north of Europe. Mr. Knott found variations in the 
position of the luminous sector to the extent of more than fifty degrees. 
Star-Cluster in the Southern Cross. — This object, described by Sir John 
Herschel as resembling a splendid piece of jewellery (the stars in it being- 
compared, from their various and beautiful tints, to sapphires, rubies, topaz, 
and emeralds), appears to have greatly altered of late years : one has 
changed, according to the careful observations of Mr. Abbott, from green- 
ish-white to bluish-purple ; another from green to pale cobalt ; another 
from green to ultramarine, &c. The colour of stars is, -however, so variously 
judged by different eyes, that probably the above discrepancies are due 
more to different estimations than any real change. 
Suspected Variable Star. — In searching- for one of Herschel’s triple stars, 
which could not be recognized as such by Struve, with the great Dorpat tele- 
scope, Mr. Dawes immediately perceived the looked-for companion, which 
was equally unseen by South, Sir John Herschel, and Smyth. From 
the fact of its being invisible for eighty years in powerful instruments and 
well-trained observers, and seen in the present year with a telescope of 
four inches aperture, Mr. Dawes thinks it desirable that it should be put 
down upon the list of suspected variables. The position of this object is 
It. A., 19h. 29m. ; N.P.D., 100° 32' ; the magnitudes, according to Mi - . 
Dawes, 6§, 8, and llj. 
Large Meteor. — A huge lolide made its appearance on November 27, 
which was visible in all parts of the British Islands and France. As seen 
by the writer, it appeared as a huge globe of fire of a balloon shape, almost 
YOL II. — NO. VI. T 
