64 
LORD OXMANTOWN ON THE GREAT NEBULA IN ORION. 
hardly, therefore, account for these numerous coincidences, except by supposing some 
at least of the stars to be situated nearly at the same distance from us as the nebula — 
in fact immersed in the nebulous matter. 
Evidence of Change. 
1. Variability of the Stars . — The only remark concerning the variability of a star 
which I find in Mr. Bond’s paper (page 94), refers to star 78, which he thinks is a vari- 
able star of short period. 
In Mr. Lassell’s paper I do not find anything on this subject. 
A star marked x in Sir J. Herschel’s diagram, published in 1825, was not found by 
him in 1837; perhaps this may be the same as 129„ hut as there is no list of positions 
of the stars in the paper of 1825, the identity is uncertain. Possibly this star may be 
variable. 
Although M. Liapounov’s observations were made about fourteen years after Sir J . 
Herschel’s, Struve found that the magnitudes of the stars as given by Herschel 
agreed very fairly with his (Liapounov’s) determinations, but one star (IV.), whose posi- 
tion was estimated by M. Liapounov, and at about the same time was measured by 
Mr. Lassell, does not occur in Sir John Herschel’s list, although it is so situated that 
it would not be likely to be overlooked. M. Struve examined with considerable care 
Bond’s Catalogue of Stars in this nebula with the view of identifying them, as far as 
possible, with those in Sir J. Herschel’s list. B 26 and B 27 he considers identical, and 
they are near the position of 75, but Mr. Bond appears satisfied of the existence of two 
stars here of the 17th and 18th magnitudes respectively; their positions are only about 
2-^" apart, and therefore their combined light might easily be taken for that of one of 
12-^ magnitude, which is that assigned to 75 by Struve; Herschel, however^ assigns 
to 75 the 18th magnitude, so that the star is possibly variable. 
Mr. Bond gives two stars about 11" apart near the position of 57, but no one else 
seems to have seen more than one. I have examined this part of the nebula repeatedly, 
but have never seen more than one star in this position. He also gives two stars south 
following 88, which may be identical with the two stars 91 and 91 r Mr. Hunter gives 
the two stars in his drawing, but he is not quite sure whether 91 t is not the same as 91, 
as he was not able to find the latter on the night on which he saw 91 t . 
Bond’s stars 42, 85, and 88 were not found by either Struve or Hunter ; there are 
also several others which Struve could not identify and which are not given by Hunter, 
but Struve is of opinion that some errors exist in Bond’s positions. 
Struve next examines Lamont’s catalogue of 34 stars, all of which he identifies more 
or less satisfactorily with stars of Herschel’s list, with the exception of four, viz. 4', 5', 
7', and 28* ; 4' and 7' I do not find in Hunter’s list; 5' is in very nearly the position of 
75 u in Mr. Stoney’s drawing f (I do not find any mention of this star in Mr. Hunter’s 
observations, but I am almost certain that I have seen one in this position and on the 
-edge of the nebulosity) ; 28 is not more than 15" distant from Struve’s star II. 
* See Steute’s Memoir, p. 95 ; these numbers are Lamont’s. + See diagram (Plate II.). 
