82 THE NEBULA IN ANDROMEDA. 



which they were made. The chart tlius constructed was used as 

 a guide in attempting the delineation of the nebula. 



The figure which accompanies this memoir is necessarily on 

 much too small a scale to admit of the introduction of minute de- 

 tails. Though prepared with care, in the manner just described, 

 it must remain open to future correction. The chief source of 

 error has been the difficulty of referring every portion to the same 

 standard of brightness. 



The observations generally were made under very favorable cir- 

 cumstances. In a large proportion, the altitude of the nebula 

 exceeded seventy degrees ; in more than one instance, its zenith 

 distance was less than two degrees. Those nights only were 

 employed in which the moon was absent, and the sky perfectly 

 clear. The power usually employed was one hundred and three, 

 with a field of twenty minutes. The following are the results 

 of the examination to which the nebula has been subjected. 



The nucleus is nearly centrally situated with respect to the 

 general body of light, but perhaps nearest the side following in 

 right ascension. Its appearance cannot be better described than 

 by adopting the words of Sir John Herschel already quoted. 



With high powers, minute stars are discerned on the borders 

 of the nucleus, but it has thus far yielded no evidence of res- 

 olution. About fifty stars are visible in the same field with it ; 

 no other equal space occurs within the limits of the nebula con- 

 taining so few. 



The region south-preceding the nucleus is somewhat brighter 

 than the opposite side ; this has been noticed by Smyth ; it is also 

 so represented on Harding's Atlas, whether by accident or design- 

 edly does not appear. The axis of the nebula, which is for the 

 most part strongly marked, particularly in its south-preceding half, 



