21 



SOME ADDITITIONAL OBSERVATIONS ON MOEE 



EECENT CHANGES WHICH HAVE TAKEN PLACE 



IN THE STAR r, ARGUS AND ITS SURROUNDING 



NEBULA. 



By F. Abbott, F.R.A.S., F.R.M.S., Read 12th April, 1870. 



I would remind the members present, that many of the notes 

 in this short paper are intended to answer questions that have 

 arisen in various discussions which have taken place on the 

 preceding one on the same subject read in 1868. 



These notes have been, for the most part, suggested by some 

 critical remarks, made on the subject by Sir John Herschel, 

 to which I shall presently refer. 



In continuation of the observations detailed in the commu- 

 cations referred to, I now bring under the notice of the Society 

 a third paper, with accompanying drawings, relative to this 

 singular object which has of late caused long and animated 

 discussion in the astronomical world. 



When I first bi ought the subject under the notice of the 

 Society (see Papers and Proceedings for June, 1863), I was 

 fully aware that the varied changes there recorded as having 

 taken place in the object, and particularly the fluctation of the 

 Nebula, would cause great excitement ; but did not expect it 

 would meet with the severe critical test to which it has been 

 subjected by Sir John Herschel, who, commenting on the 

 drawing at a meeting of the R.A.S., remarks that " The 

 question is not one of minute variations of subordinate 

 features which may, or may not be attributable to diiferences 

 of optical power in the instruments used by different oV)servers, 

 as in the case of the Orion Nebula — but of a total change of 

 form and character-— a complete subversion of all the greatest 

 and most striking features, accompanied with an amount of 

 relative movement between the star and the Nebula, and of 

 the brighter portions of the latter i^ifer se, which remind us 

 more of the capricious changes of form and place in a cloud 

 drifted by the wind. The great increase of light that has taken 

 place in the brightness of the Nebula is very remarkable ; it 

 could not be seen at all by the naked eye, when I was at the 

 Cape, but the changes which have taken place in the figure of 

 the Nebula are still more startling. Mr. Abbott supplies two 

 pictures, one representing the appearance of the Nebula as seen 



