108' On 7} Argils and Nebula. 



of this nebula are doubtless situated at widely different 

 distances from the observer. 



This second sketch of Mr. Le Sueur's contains little else 

 that differs from his first, except that in the corner he makes 

 a memorandum : " Noticed a bridge at + Jan. 31, 70 — 

 never sure (?) before — may be small stars." But as he notes 

 on his first sketch : " Bridge at ^ in channel — no doubt at all 

 — April — July, 1869." The truth probably is that a bridge 

 existed at both these periods, which had been withdrawn in 

 the interval, as my subsequent notes may explain. 



Last month, after concluding my year's observations on 

 this nebula — then becoming too low sub polo to observe — I 

 unexpectedly came upon a third sketch (No. 3) of Mr. Le 

 Sueur's, among some of his stray papers. Although un- 

 finished — indeed, just commenced — I look upon it as the 

 most valuable of the three, for, so far as it goes, it entirely 

 corroborates the evidence of one change since observed by 

 myself in the nebula, and sketched by me in entire ignorance 

 of this sketch, thus supplying so unexpected yet stringent a 

 link between his observations and mine, that hereafter no 

 suspicion of optical bias as affecting the more important 

 changes observed can enter my mind. 



After dotting down on his sketch all tha stars observed 

 near r] — nearly three times outnumbering Herschel's in that 

 space — which agree entirely with my latest sketch, even to 

 the position of a minute triple star w / and close to rj shown 

 double by H., and trii^le, but dAfferently placed in 1871 

 by Mr. Bussel, of Sydney Observatory, Mr. Le Sneur 

 proceeds about March '70, to pencil the outline of the lem- 

 niscate, and at 2' 30" ]) V N oi rj shews the outline of a gulf 

 or cleft commencing at the star 634 H. This star is one of 

 those landmarks described by H. in the year 1838 as being- 

 near the margin. Mr. Le Sueur's sketch shows it nearly in 

 mid-channel ; 616 H, however, being still involved in nebula. 

 Here probably Mr. Le Sueur saw the commencement of the 

 intricate changes since observed by me in the n p loop of the 

 leraniscate, and paused to unravel them before proceeding. 



In December, 1870, rj was again sufficiently high to observe, 

 and I took the first opportunity of turning upon it on the 

 27th, when, on comparison with Mr. Le Sueur's sketches 1 

 and 2— for No. 3 had not then been found — showed marked 

 changes in the nebula, and I at once commenced my first 

 sketch, No. 4, confining myself to the neighbourhood of 

 the lemniscate, where the most important changes seemed to 



