Astronomical Notes. 141 



much easier than formerly, are remarkable instances ; others 

 of them again are not easily found without circles. The fixity 

 and conspicuousness of the present object would render it a 

 far superior criterion, were it not unfortunately situated so far 

 S. that, like the comites of Antares and Sirius, it becomes 

 rather an atmospheric than an instrumental test. On really 

 steady nights, however, it affords an excellent trial. I have 

 often seen it divided, and occasionally with a good black sepa- 

 ration, with 461, and even 212 will sometimes split it. The 

 smaller component has a ruddy hue. It is readily made out as 

 a moderately bright star lying sp from 8, the uppermost of the 

 three in the belt, about as far off as the belt is long. 



PLANETAKY NEBULA. 



In the Intellectual Obseevee for March, 1864, p. 139, 

 mention is made of my having missed an extremely faint 

 planetary nebula among the northern stars of the fine cluster 

 46 M (Argus). A remark by Mr. Knott (to whose kind assist- 

 ance the present paper owes much of its details) induced me 

 to examine it more carefully, when I found it in a low-power 

 field (65) with so little difficulty that I can only suppose that 

 my eye, which seems to fail me in the search for minute objects 

 near much brighter ones, had previously been distracted by the 

 general sparkling of the more brilliant assemblage. Till once 

 seen, however, it could hardly be called obvious with 5^ inches 

 of aperture. I saw it as a feeble and very ill-defined luminous 

 disc, with a star about 10 mag. on its sf border, and some 

 sparklings in it as of 13 or 14 mag. stars. H., who, in 1833, 

 calls it " exactly round, of a faint equable light," says it has 

 a very minute star a little 1ST. of its centre, and is not bright in 

 the middle, nor fading away, but a little velvety at the edges. 

 Lassell, who examined it at Malta in 1853 with his noble 

 24-inch speculum, and speaks of it as "an astonishing and 

 interesting object," says it has a star or stellar nucleus nearly, 

 but not quite, in the centre, with another fainter star rather 

 nearer the centre than the circumference ; and that the nebula 

 seems to retreat from the larger star, leaving it on a much 

 darker ground than the external part of the nebula : two or 

 three points or bright spots in the nebula also occasionally 

 catch the eye. It appears rather singular that the star towards 

 the sf edge, so readily seen by Mr. Knott and myself, should 

 find no place in the descriptions of either of our two great 

 observers. Possibly it may be variable. Sm. says most 

 appropriately that the impression given by this nebulosity is 

 f ' that of awful vastness and bewildering distance" ; but this 

 is on the supposition of its starry nature. If gaseous, it may 



