27 



■n AEGUS. 



ALTERATIONS WHICH HAVE TAKEN PLACE IN THE 



NEBULA, &c., SURROUNDING 77 ARGUS, FROM FEBRUARY, 



1871, TO FEBRUARY, 1872. 



By F. Abbott, F.E.A.S., F.E.M.S. 



(Read llth June, 1872.) ■ 



If it were not for the certainty tliat many and important 

 changes have of late years taken place in connection with the 

 star y] in Argo Navis, and the surrounding nebula, I should 

 feel some diffidence in replying to the queries set forth by 

 the late Sir John Herschel and tlie Astronomer Eoyal. 



Sir John Herschel, when he wrote the Cape observations, 

 expressed a desire, in different parts of the book, that any 

 astronomer who followed him would carefully observe certain 

 points in connection with nebulous matter, in order to ascer- 

 tain if any such alterations as those referred to did take place. 

 If Sir John, at the time he wrote, had thought the nebula 

 inflexible, he certainly would not have expressed such a desire. 

 Why, then, is this wish ignored ? and against such observa- 

 tions as have been made on the nebula uj) to the present 

 time, why has so much negative evidence been offered by 

 astronomers who have not even seen the object ? and who 

 offer no inductive evidence to disprove the alterations, but 

 from the evidence they have examined (what evidence ?) have 

 come to the conclusion that no change has taken place. This 

 result was not arrived at by the Astronomer Eoyal after 

 examining the evidence produced. 



It is scarcely likely that Australian astronomers will relax 

 observing so interesting an object, which they have the oppor- 

 tunity of seeing every fine night through the year, and of 

 the changes in which much strong corroborating evidence is 

 being adduced when only brought in comparison with the 

 few casual observations made at Bangalore and Cordoba ; 

 or with any such reasoning as that offered by Mr. Procter, 

 which must have been conceived by him since he wrote the 

 article (" The Great Nebula in Argo ") in Fraser's Magazine 

 for December, 1868. This kind of reasoning reminds me of that 

 fine double star tj Coronae first seen double by the late Dr. 

 Herschel. Many a star-gazer lias turned out on a bitterly 

 cold night to inspect -n Coronae, and, being unable to divide it, 

 arrived at the conclusion that no one had seen it double. 



In a letter received from Mr. Severn, dated 29tli June, 

 1870, the following passage occurs : — " Have you seen the tenth 

 and new edition of the Outlines of Astronomy, in which it is 



