18 On the Nebula around Eta Argus. 



drawing with his own in every possible way ; he could not, 

 however, identify any of the stars, and could make nothing of 

 the drawing. 



In !R. A. S. Notices for 1868, he remarks : — " It is much to be 

 wished that some southern observer, furnished with an equa- 

 toreally mounted telescope, would without further delay, set to 

 work and map down the stars visible within this most interesting- 

 area, down, at least, to the 10th or 11th magnitude. Possibly, I 

 may have done Mr. Abbott injustice by assuming that his diagram 

 is intended to convey any delineation at all of the stellar contents 

 of his fields of view ; or anything beyond the forms of the 

 nebulous masses as existing among scattered stars.- But the 

 question once raised is of the last importance, and must be set- 

 tled. The question here is not one of minute variations in 

 subordinate features which may, or may not be attributable to 

 differences of optical power in the instruments used by diffei'ent 

 observers, as in the case of the nebula in Orion (the only one at 

 all comparable with it in magnitude, complexity, and brightness), 

 but of a total change of form and character — a complete sub- 

 version of all the greatest and most striking features, which 

 reminds us more of the capricious changes of form and place of a 

 cloud drifted by the wind, than of anything before witnessed in 

 the Sidereal Heavens." 



In August of the same year, Lieutenant Herschel, having gone 

 out to India in charge of one of the Eclipse expeditions, took the 

 opportunity of observing Eta Argus nebula. At his father's 

 request fifty of the principal stars were measured, and identified 

 with stars in the Cape Monograph without difficulty ; and several 

 drawings were made of the nebula, showing an enclosed space 

 near Eta, and other features much more like the Cape drawing 

 than Mr. Abbott's. He remarked, also, the increased visibility of 

 the nebula, bvit said there did not appear to be any very remark- 

 able change in the distribution of the stars or nebula so far as 

 the part immediately around Eta is concerned. E. A. S. Notices 

 for 1869. 



In 1869 Mr. Le Seur turned the large Melbourne reflecbor 

 upon this nebula, and with the speculum, as it then was, could 

 not recognise any nebula immediately round Eta, which was con- 

 sequently thought to be in the dark space. I have not seen his 

 drawing, and cannot, therefore, say what features he noted ; 

 before he left he repolished the speculum, and the telescope 

 now performs much better. With it Mr. M'Greorge has been 

 able to see that Eta is still in the nebula ; and in his drawing, 

 which includes only the nebulous mass in which the lemniscate is 

 situated, shows the very dense part near and north of Eta, the 



