110 On 7] ArgiXs and Nebula. 



again approaching nearly to that drawn by H. in 1838. 

 The very faint nebula S p r], does not appear at all until 2' 

 dist. where the outline of the faint nebula now seems to 

 commence. The outlying portions preceding lemniscate 

 also show slight changes, but to these I have not devoted so 

 close an attention, deeming it better to keep a close and 

 unremitting watch over the central portions, than to distract 

 the mind with too great a variety of details, and what I 

 have sketched, however carefully, I confirm by verbal 

 description in my notes on the spot, and add any impressions, 

 however trivial, which strike me at the time, as such 

 impressions are sometimes found to prove of the greatest 

 value in retrospect. 



On the 17th January, of this year, I note : Power 520 

 shows distinct nebulosity surrounding -q itself much con- 

 densed towards rj chiefly in direction of lemniscate. The 

 margins of the channels and lemniscate come out in good 

 distinct relief, just as I have already sketched them ; the 

 vacant spaces showing almost black. 



Spectrum of nebula very faint, with usual lines ghostly 

 and fitful. 



Spectrum of -n hazy and unsatisfactory, with diffused 

 light, although other stars appear distinct enough. Could 

 not see the slightest appearance of bright lines, but fancied 

 I detected with wide slit absorption bands in position of 

 nebular lines, but too chaotic and indistinct for measurement 

 although attempted frequently. 



Can 7^'s light be absorbed by surrounding nebula ? At 

 the time Le Sueur observed (December 1869), he says, " No 

 nebula is apparent about tj, although sky did not appear so 

 black as in lemniscate spaces, and rj gave bright lines." 



Next evening (18th January) Mr. EUery confirmed my 

 observations and verified sketch. Neither he nor Professor 

 Smith, who was also present, recognised the spectrum of rj 

 when shown in the telescope as the same which they had 

 seen the year before, and could find no bright lines. I 

 again imagined I saw the same ghosts of absorption lines 

 in the positions of the usual bright lines of the nebula. 



On the 18th May my notes describe the appearance of a 

 small star in the oval space N. p. -q before described (owing 

 to the nebula becoming still thinner in that spot) forming 

 the head-star to a sort of miniature Orion of minute stars : 

 a pentagon enclosing seven stars, five of which were seen by 

 Le Sueur, none by H. The notes then proceed : " The 



