OF THE COSMOS. VARIABLE STA11S. 173 



In 1677 Halley had found r\ Argus of the 4th magnitude ; 

 in 1751 Lacaille found it already of the 2d. Afterwards the 

 star returned to its earlier fainter intensity, for Burchell, 

 during his residence in Southern Africa in 1811 1815 

 found it of the 4th magnitude. From 1822 to 1826 

 Tallows and Brisbane saw it of the 2nd magnitude ; and in 

 February 1827, Burchell, who was then at St. Paul in Brazil, 

 found it of the 1 st magnitude, and quite equal to a Crucis. 

 After a year it returned to the 2nd magnitude; it was 

 found so by Burchell in the Brazilian town of Goyaz on the 

 29th February, 1828, and was so entered by Johnson and 

 Taylor in their registers from 1829 to 1833. Sir John 

 Herschel at the Cape of Good Hope also estimated it from 

 1834 to 1837 at between the 2nd and 1st magnitude. 



But on the 16th of December, 1837, when the last named 

 celebrated astronomer was preparing to make photometric 

 measurements of the numberless telescopic stars of the llth 

 to the 16th magnitudes which fill the fine nebula around 

 i) Argus, he was astonished at finding this often observed 

 star increased to such an intensity of light, that it almost 

 equalled the brightness of a Centauri, and surpassed that of 

 all other stars of the first magnitude except Canopus and 

 Sirius. It had attained the maximum of its brightness on 

 that occasion on the 2nd of January, 1838. It soon became 

 fainter than Arcturus, but still surpassed Aldebaran in the 

 middle of April 1838. It went on decreasing until March 

 1843, always continuing, however, to be a star of the 1st 

 magnitude, but we then find, particularly in April of the same 

 year, that the light began to increase again to such a degree, 

 that according to the observations of Mackay at Calcutta, and 

 of Maclear at the Cape, TI Argus became brighter than Canopus, 



