relating to the Construction of the Heavens. 323 
** from a careful observation of this lucid spot, something may 
be concluded concerning the nature of it.” 
In January 1783, the nebulous appearance differed much 
from what it was in 1 780, and in Septemper it had again un- 
dergone a change in its shape since January. 
March 13, 1811. With a view to ascertain such obvious 
alterations in the disposition of the nebulous matter as may be 
depended on, I selected a telescope that had the same light 
and power which thirty-seven years ago I used, when I made 
the above-mentioned drawing ; and the relative situation of 
the stars remaining as before, I found that the arrangement 
of the nebulosity differs considerably. The northern branch 
N still remains nearly parallel to the direction of the stars 
a b ; but the southern branch S is no longer extended towards 
the star d ; its direction is now towards e, which is very faintly 
involved in it. The figure of the branch is also different ; the 
nebulosity in the parallel P F of the three stars being more 
advanced towards the following side than it was formerly. 
I compared also the present appearance of this nebula with 
the delineation which Hu yg hens has given of it in his Sy sterna 
Saturnium , page 8, of which fig. 38 is a copy. The twelve stars 
which he has marked are sufficient to point out the arrange- 
ment of the nebulous matter at the time of his observation. 
By their situation we find that the nebula had no southern 
branch, nor indeed any to the north, unless we call the nebu- 
losity in the direction of the parallel a branch ; but then this 
branch is not parallel to a line drawn from a to the star b; 
moreover the star/ is now involved in faint nebulosity, which 
also reaches nearly up to g, and quite incloses h. The star b 
T t 2 
