242 COSMOS. 



the Cape of Good Hope, estimated it as being between the 

 2nd and 1st magnitude, from 1834 to 1837, 



When, on the 16th of December, 1837, this famous astro- 

 nomer was preparing to take the photometric measurements 

 of the innumerable telescopic stars, between the llth and 

 16th magnitudes, which compose the splendid nebula around 

 17 Argus, he was astonished to find this star, which had so often 

 before been observed, increase to such intensity of light that 

 it almost equalled the brightness of a Centauri, and exceeded 

 that of all other stars of the 1st magnitude, except Can opus 

 and Sirius. By the 2nd of January, 1838, it had for that 

 time reached the maximum of its brightness. It soon became 

 fainter than Arcturus; but in the middle of April, 1838, it 

 still surpassed Aldebaran. Up to March, 1843, it continued 

 to diminish, but was even then a star of the 1st magnitude ; 

 after that time, and especially in April, 1843, it began to 

 increase so much in light, that, according to the obser- 

 vations of Mackay at Calcutta, and Maclear at the Cape, 

 17 Argus became more brilliant than Canopus, and almost 

 equal to Sirius. 17 This intensity of light was continued 

 almost up to the beginning of the present year (1850). 

 A distinguished observer, Lieutenant Gilliss, who com- 

 mands the Astronomical Expedition sent by the Govern- 

 ment of the United States to the Coast of Chili, writes 

 from Santiago, in February, 1850: " 17 Argus, with its 

 yellowish-red light, which is darker than that of Mars, is 

 at present next in brilliancy to Canopus, and is brighter 

 than the united light of a Centauri." 18 Since the appearance 



17 Compare Sir John Herschel's Observations at the Cape, 

 71-78 ; and Outlines of Astron., 830 (Cosmos .vol.i. p. 144). 



18 Letter of Lieutenant Gilliss, astronomer of the Observa- 

 tory at Washington, to Dr. Fliigel, Consul of the United 

 States of North America at Leipsic (in manuscript). The 



