There is a very remarkable variable star in the Southern Hemisphere known as Eta Argûs. It lies in the midst of the great nebula in Argo, and the history of its fluctuations in light is very interesting. Observed by Halley in 1677 as a star of the fourth magnitude, it was seen of the second magnitude by Lacaille in 1751. After this, it must have again faded, for Burchell found it of only the fourth magnitude from 1811 to 1815. From 1822 to 1826 it was again of the second magnitude, as observed by Fallows and Brisbane; but on February 1, 1827, it was estimated of the first magnitude by Burchell. It then faded again, for on February 29, 1828, Burchell found it of the second magnitude. From 1829 to 1833 Johnson and Taylor rated it of the second magnitude; and it was still of this magnitude, or a little brighter, when Sir John Herschel commenced his observations at the Cape of Good Hope in 1834. It does not seem to have varied much in brightness from that time until December, 1837, when Herschel was astonished to find its light “nearly tripled.” He says: “It very decidedly surpassed Procyon, which was about the same altitude, and was far superior to Aldebaran. It exceeded Alpha Orionis, and the only star (Sirius and Canopus excepted) which could at all be compared with it was Rigel.” From this time its light continued to increase. On the 28th December it was far superior to Rigel, and could only be compared with Alpha Centauri, which it equaled, having the advantage of altitude, but fell somewhat short of it as the altitudes approached equality. The maximum of brightness seems to have been obtained about the 2d of January, 1838, on which night, both stars being high and the sky clear and pure, it was judged to be very nearly matched, indeed, with Alpha Centauri. In 1843 it again increased in brightness, and in April of that year it was observed by Maclear to be brighter than Canopus, and nearly equal to Sirius! It then faded slightly, but seems to have remained nearly as bright as Canopus until February, 1850, since which time its brilliancy gradually decreased. It was still of the first magnitude in 1856, according to Abbott, but was rated a little below the second magnitude by Powell in 1858. Tebbutt found it of the third magnitude in 1860; Abbott a little below the fourth in 1861. Ellery rated it fifth magnitude in 1863, and Tebbutt sixth magnitude in 1867. In 1874 it was estimated 6.8 magnitude at Cordoba, and only 7.4 in November, 1878. Tebbutt’s observations from 1877-86 show that it did not rise above the seventh magnitude in those years, and in March, 1886, it was rated 7.6 magnitude by Finlay at the Cape of Good Hope. This seems to have been the minimum of light, for in May, 1888, Tebbutt found that it “had increased fully half a magnitude” since April, 1887. The star is very reddish in color.