130 VAEIABLE STAES IN SOUTHERN HEMISPHERE, 



The following extract, from Sir John HersehelPs " Outlines of 

 Astronomy," shows the changes that have been recorded of it 

 previous to 1844 : 



" In the time of Halley (1677) it appeared as a star of the 

 fourth magnitude. Lacaille, in 1751, observed it of the second. 

 In the interval from 1811 to 1815 it was again of the fourth ; 

 and again, from 1822 to 1826, of the second. On the 1st of 

 February, 1827, it was noticed by Mr. Burchell to have increased 

 to the first magnitude, and to equal Alpha (a) Crucis. Thence, 

 again, it receded to the second ; and so continued until the end 

 of 1837. All at once, in the beginning of 1838, it suddenly 

 increased in lustre so as to surpass all the stars of the first 

 magnitude except Sirius, Canopus, and Alpha (a) Centauri, which 

 last star it nearly equalled. Thence, it again diminished, but 

 this time not below the first magnitude until April, 1843, when 

 it had again increased so as to surpass Canopus, and nearly equal 

 Sirius in splendour." 



I have myself watched the variations of this star for some 

 years past with considerable interest. In 1854 it was a very 

 conspicuous object west of the Southern Cross, equilibrating 

 as it were the two bright stars of the Centaur with that con- 

 stellation. The most casual observer of the heavens might now 

 miss the bright object which was then so conspicuous. The 

 following comparisons, made by me in July of that year, may be 

 interesting in conjunction with the present insignificant ap- 

 pearance of the star : Of Alpha (a) Centauri, Beta (/3) Centauri, 

 Alpha (a) Crucis, and Eta (77) Argus, the first was by far the 

 brightest. Beta (/5) Centauri and Eta (77) Argus were about 

 equal in brilliancy. It was difficult to judge of the comparative 

 brightness of these two, but I considered the latter to be somewhat 

 the brighter. Eta (77) Argus was somewhat brighter than Alpha 

 (a) Crucis. The star in question now appears as one of ftbout 

 the 4| magnitude. A marked diminution of its lustre has taken 

 place since May, 1860. About that time I pointed out to the 

 Rev. W. Scott, the Government Astronomer, the remarkable 

 changes that had taken place in its lustre ; and at his recommen- 

 dation I compared its magnitude with stars within range of the 

 European observatories. I found some difficulty in making this 



