On r) Arg^s and Nebula. 109 



be taking place, and where, from the brightness of the nebula 

 and the amount of A-arying detail, the best field offered for 

 the powers of the Great Telescope. For the changes of which 

 I have spoken, and those of which I have yet to furnish a 

 description, are utterly beyond the powers of detection of 

 every other instrument in the southern hemisphere. With- 

 out the Great Telescope another thirty years might have 

 elapsed without producing changes sufficiently great to be 

 within the compass of ordinary observatories. 



Ignorant then of Mr. Le S.'s third sketch, and diffident of 

 describing and drawing what I saw from the mere mag- 

 nitude of the changes which had appeared in so short a 

 time, I made a rapid sketch of the nebular portion of the 

 lemniscate and neighbourhood, only putting in such stars 

 as were necessary to guide the eye. The gulf at 63-i H was 

 one of the first features sketched, and my drawing shews 

 not only that this star is in mid-channel, but that 616 -ET 

 also is left nearly clear of nebula. The promontory which 

 Mr. Le S.'s second sketch shews still I'eraainingf, has detached 

 its extremity to form an island of nebula, in which I note a 

 star-like nucleus, and this, with the remnant of the 

 promontory, seems to direct itself still more towards the 

 opposing cape, which, however, does not appear so prominent 

 as in Sketch 2. This, and the neighbouring parts of this 

 margin of the lemniscate appears to keep the same hard 

 definite outline which is presented by Sir J. H. but at 1| p 

 3'= side of each square, 1|- N, the outline seems encroaching 

 upon the lemniscate, and leaving a little nearer 77 an oval 

 patch of thinner nebula than that which surrounded it. 

 Southwards also, the nebulous outline seems to be curdling 

 and breaking up, and is evidently much less dense than 

 drawn by H., and a little less so than drawn by Le S. 



But in the N p loop of the lemniscate changes perhaps still 

 more evident are going on. The outUne preceding H 670, 

 which in Sketch 1 largely bulged into the lemniscate to meet 

 the isthmus, and which in Sk. 2 and Sk. 3 is slowly with- 

 drawing itself, has still further retracted in a iV p direction ; 

 the outline p this is withdrawing also in a N 'p direction, 

 and two condensations are taking place in the faint nebula 

 which fills the N p loop of the lemniscate. The curved N p) 

 arm of the V shaped appendage has turned itself into a N 

 and B direction, and botli arms appear straighter than in 

 Sk!s 1 and 2. A faint branch of nebula also appears 1| N 

 of -q, and proceeds in a / direction, giving an appearance 



