104 



Anniversary Meeting. 



[Nov. 30; 



The great Melbourne Telescope arrived at its destination in November 

 1868, without injury of any importance — which, perhaps, could hardly 

 have been expected after a voyage of 1 6,000 miles, for an instrument at 

 once so massive and so delicate ! 



The Visitors of the Melbourne Observatory thought it advisable to adopt 

 the suggestion of Dr. Robinson to provide the telescope with a covering, 

 and for this purpose they preferred the second of the plans which he pro- 

 posed — a rolling roof. This appears to have been satisfactorily executed. 

 It protects the telescope completely, and can be removed by a single work- 

 man, leaving the telescope fully exposed to the sky. 



In erecting the instrument some trifling difficulties seem to have been 

 experienced, and it was not fit for actual work until the beginning of last 

 June, which is midwinter there, a season when cloudy weather prevails to 

 an extent which we were scarcely prepared to expect, and which is stated 

 to have been this year excessive. For these reasons the habitual work of 

 the telescope had not been commenced up to September. 



Its performance since erection does not appear to have given altogether 

 the same satisfaction at Melbourne that it did at Dublin ; but the defects 

 complained of may arise partly from an imperfect knowledge of the 

 principles of the instrument and inexperience in the use of so large a tele- 

 scope, partly from experimental alterations made at Melbourne, and partly 

 from atmospherical circumstances. Those who are acquainted with the 

 difficulties which Sir J. F. W. Herschel experienced at the Cape, will not 

 be surprised that they should be felt at Melbourne to a much greater ex- 

 tent, on account of the far greater size of the speculum. But I have no 

 doubt that if the instrument be kept in its original condition and as care- 

 fully adjusted as it was at Dublin, it will perform as well in ordinary 

 observing-weather. 



The high impression of its power produced by the trials which were 

 made of it when at Dublin, is maintained by a sketch of a portion of the 

 Great Nebula near i) Argus, made by M. Le Sueur during two nights in 

 June last. 



Some change in this nebula from the time when it was described by Sir 

 J. F. W. Herschel had been indicated by Mr. Powell and other observers, 

 though with instruments so much inferior in power to his 20-foot re- 

 flector, that little reliance could be placed on them ; however, here the 

 evidences of change are indisputable. The peculiar opening in the nebula, 

 which Sir John Herschel has compared to a lemniscate, is still very 

 sharply marked, but its shape and magnitude have altered. Its northern 

 extremity is opened out into a sort of estuary ; one of the remarkable con- 

 strictions seen in 1834 has disappeared, and the other has shifted its place. 

 Two stars which were then exactly on the edges of the opening are now 

 at some distance within the bright nebulosity ; the nebula has become 

 comparatively faint near rj Argus. 



Another remarkable change is the formation of a V-shaped bay south 



