84 
POPULAR SCIENCE REVIEW. 
will be well watched by the Lunar Committee, whose last circular requests 
that observations of the large white spot should be resumed, with a view of 
ascertaining the state of the large shallow crater, and of the orifice (small 
crater) within it. Measures of the small crater should be made at least once 
in every lunation. Observations of the mountain, Gamma Posidonius, and 
of the black point on its summit, are also asked for. There is work here for 
many of the powerful instruments now in the hands of amateurs ; and Mr. 
Birt, who has devoted a large amount of attention to the lunar surface, 
recommends that each spot should be treated separately, with as much care 
as each binary star. Whether any real physical change may be discovered 
it is impossible to say, but that peculiar variations do take place in some 
craters more than in others, appears certain. If the inquiry should terminate 
in anything tending to show atmospheric action on the moon, the result 
would be a discovery of the utmost importance. 
The Parallax of Sirius. — In a paper presented to the Astronomical Society 
at the last meeting, M. Cleveland Abbe has discussed the observations made 
at the Cape of Good Hope, between the years 1856 and 1863, with the ob- 
iect of obtaining a more accurate determination on this subject. The result of 
the investigations is corroborative of the conclusion drawn by Mr. Henderson, 
in vol. xi. of the Memoirs of the Royal Astronomical Society, that ‘Hhe 
parallax of Sirius is not greater than half a second of space.” 
Large Object-glasses. — It was announced by the President, at the meeting 
of the Royal Astronomical Society on the 8th of November, that the large 
object-glass of twenty-five inches diameter, in course of working by the 
Messrs. Cooke of York, was at length completed ; and that the severe test 
of dividing Gamma 2 Andromeda had been satisfactorily sustained by it. 
This is a subject quite worthy of notice in the list of Astronomical Events 
for the Year 1867, as the completion of this immense glass has been long 
and anxiously looked forward to. It must, however, be some time before it is 
in a position for its great capabilities to be made use of. - We have, however, 
other glasses of great size j eight and nine inch aperture telescopes are now 
frequently to be met with, both in public and private observatories ) but all 
are at present eclipsed by the telescopes used by Mr. Buckingham, of Wal- 
worth, who gave an account at the meeting of the Society above referred to 
of the discovery of some minute companions to Vega with a 20-inch aper- 
ture telescope, the object-glass of which, however, he had just replaced by 
one of 21^ inches, both having been made by Mr. Wray, of Highgate. 
The discovery of these companions to Vega had been brought before the 
public previously in the Astronomical Register, a notice of which will be 
found in our summary for October last, p. 443. Mr. Be La Rue stated that 
it was not only necessary to turn both the object-glass and the eye-piece 
round, but that the objects should be looked at when in different parts of 
the heavens, to guard against their being the production of flexm’e in the 
telescope tube itself. 
The Late Earl of Posse. — No name among those connected with modern 
astronomy is more widely known than that of Lord Rosse. To him the 
science is greatly indebted, not to his scientific or mathematical acquire- 
ments, but to the fact that he was one of those, rarely to be met with, who, 
having large means, devoted them liberally to the cause of science. Lord 
