76 Dr. HersChel’s Obfervations 
When I examined the clufter of ftars, following the head of the 
great dog ( a ), I found on the 19th of March, 1786, that there 
was within this clufter a round, refolvable nebula, of about two 
minutes in diameter, and nearly of an equal degree of light 
throughout (£). Here, confidering that the clufter was free 
from nebulofity in other parts, and that many fuch clufters, as 
well as many fuch nebulae, exift in divers parts of the hea- 
vens, it appeared to me very probable, that the nebula was 
unconnected with the clufter ; and that a fimilar reafon would 
as eafily account for this appearance as it had refolved the phe- 
nomenon of the double ftar near e Bootis ; that is, a cafual 
Atuation of our fun and the two other objeCts nearly in a line. 
And though it may be rather more remarkable, that this ftiould 
happen with two compound fyftems, which are not by far fo 
numerous as Angle ftars, we have, to make up for this Angu- 
larity, a much larger fpace in which it may take place, the 
clufter being of a very conAderable extent. 
On the 15th of February, 1786, I difcovered that one of 
my planetary nebulae (c), had a fpot in the center, which was 
more luminous than the reft, and wdth long attention, a very 
bright, round, well deftned center became vifible. I remained not 
a Angle moment in doubt, but that the bright center was con- 
nected with the reft of the apparent difk. 
In the year 1785, the 6th of October, I found a very bright, 
round nebula, of about if minute in diameter (dQ. It has a 
large, bright nucleus in the middle, which is undoubtedly 
( a ) RA. 7 32 1. PD. 104 18. 
( h ) 7 3 *5- I0 4 IS- 
(') 17 58 25. 23 22. 
<y) 3 3 ° 35 - 109 15- 
■ connected 
