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The “Gem” Cluster in Argo. 
By H. C. Russert, B.A., F.R.A.S. 
[Read before the Royal Society of N.S. W., 4 June, 1879.] 
Tue small cluster of stars which I have ventured to call the 
ean at least be little doubt that the time which Sir John Herschel 
devoted to the remarkable nebula and cluster about 7 Argus 
corded by Lacaille, who entered it as No. 4,375 of his catalogue 
simply as a nebula; without any remark as to its character or the 
size of the stars. "Br isbane observed it twice, and Daas it first 
as No. 3,105 of 7th magnitude, and the remark—“ In the centre 
of a cluster of very small stars very close together, and about 6 
~ minutes in diameter.” Again, as No. 3,107 with no magnitude, 
but as a nebula, or star, in the ‘sisi of a cluster. Dunlop, who 
observed clusters and nebule with a reflector of 9 inches 
aperture and 9 feet focus, erected at his’ private house, enters 
this object as No. 321 in his catalogue, with the remark—“A ve 
small cluster of very small stars, figure round, about 4 minutes in 
“A fine, bright, rich, not very large cluster,” and leaves it 
Seat a hint of the num imber or magnitudes of the stars. Such is 
e€ account which, so far, astronomers have given of this 
beautiful — It is true the dimensions are not large (about 
7 minu in diameter), but the gud and Saker 0 
a b 
little << Gem,” which, in the estimation of many observers, is quite 
equal to the well- known « Crucis. My own estimate is that it is 
striking object, and it is certainly not so rich in colour. 
a 
. fh bea oe the red star is much larger than the corresponding one 
7 magni- 
« Crucis, and all the bright stars, consisting of three of 
