32 A. W. Roberts.— Variable Star observing, &c. 
would seem the most satisfactory explanation, for~ 
in 1811 it was of the 4th Mag., while recent 
measurements by Mr. Finlay shew it to be of 
the 7th Mag. y» Argus is the central star of a 
nebula that has long been suspected of change. 
These surmisings have received the most remark-- 
able confirmation. A photograph of the Nebula 
taken at Sydney quite recently shews that the 
portion which Herschel in 1837 deemed brightest 
has quite disappeared. 
Future observation will no doubt prove that in 
this part of the Milky Way there is a region of 
the most stupendous change. 
How stupendous even the change in» Argus is- 
may be understood from the fact that it now 
shines with nearly two thousand times less light 
than it did in 1843. 
R MuscaE—R.A. 12 35™ Dec. — 68°48’, max.—6°6, min. =7°4. Period: 
x PAVONIS—R.A. 
21 hours 21°5 mins. 
This star will well repay observation as its rapid,. 
though small, changes are most interesting. The 
maximum for any date can be calculated from: 
the following elements where ¢ is the number 
of revolutions from the epoch : 
Aug. 26°3 + -89 t. 
If the parallax of this star be less than 0-1” what 
an astounding velocity of rotation—supposing 
this to be the cause of the regular variation--- 
R. Muscze must have! 
18 45™ Dec. 67°-22’, max. 4:0, min. 51. The 
period of this star is 9°1 days and the light curve- 
extremely regular. 
Several maxima have been observed slightly 
greater than 4°0 Mag. 
The elements for minimum period are : 
July 10°96 + 24 + 9°14, 
And for maximum : 
July 6°35 4°15 + 914. 
