Position. 



Distance. 



= 208° 15' 

 = 210 (est.) 



218 .0 



216 .4 



215 .4 



10".9 

 10 (est.) 

 10 (est.) 

 14 (est.) 

 10 .1 



212 OBSERVATIONS ON NEBULA 



for AB, 218°.6, though, from the nature of the deduction, not much to be de- 

 pended upon. An observation with the micrometer also occurs in the Journal, 

 as follows: " Oct. 4. Tv/o measures of AB, sp 52° 30', and 55° 30' " the mean 

 of which = 216°.0. Arranging all the measures of this star in order of time, we 

 have 



Herschel and South, 1823.5 61° 45', s p 



Sir J. Herschel, 1827 GO s p 



, 1831 

 Mean of the above, 1839.7 



The conjecture of Sir J. Herschel with regard to the change of position of 

 this star (see Art. 57, " Fifth catalogue of double stars,") seems, therefore, not to 

 be confirmed. 



63. The nebula IV. 41, and V. 10, 11, and 12, of Sir Wm. Herschel's cata- 

 logues are identical. Sir J. Herschel seems to have recognised only the former. 

 And it appears that Sir Wm. Herschel supposed them different nebulae, from 

 his assigning to them two different places in his catalogues. 



64. The observations on h. 2092 and 2093, by former observers, are in great 

 confusion inter se. Of the two " compound systems or milky ways" in Sir 

 Wm. Herschel's first quoted paper, the " second " answers to the bifurcate, and 

 the " third'" to the network portion of this nebula. If the descriptions there 

 given did not show conclusively that this was the case, the places assigned 

 would remove all doubt. Again; in his first catalogue of 1000, he repeats the 

 description of the third milky way, under the title of V. 14, which must there- 

 fore correspond to the netrvork; and the place he assigns, when reduced, be- 

 comes R. A. 20'" 50™ 0, Decl. -f- 30° 50', which exactly coincides with the 

 brightest point of this portion. Sir J. Herschel seems to have overlooked or 

 mistaken some of these observations, by applying the synonym V. 14 to the bi- 

 furcate portion, and calling the network " Nova," whereas both these suppo- 

 sitions the above comparison shows to be unwarrantable. 



There is also some reason to believe, from the description in his paper of 

 1811, Art. 59, that the elder Herschel saw the faint band which I have shown 

 connects these two portions, or, in other words, traced out the whole nebula; the 

 "figure 1," however, to which he refers so immediately, exhibits no trace of 

 resemblance to the object, as seen by us, nor is the difference such as could be 

 caused by any difference in telescopes. Nor is it at all in favour of this belief, 



