300 Dr. Hersohel’s Astronomical Observations 
Y. 19 is “ A considerably bright nebula about 15' long and 
e< 3' broad ; its length is divided in the middle by a black divi- 
“ sion at least three or four minutes long.” See fig. 12. 
The nebulous matter of this nebula is probably a ring in a 
very oblique position with respect to the line of sight. 
II. 646 is “ A pretty bright, large nebula, of an irregular 
“ figure; it is unequally bright.” 
The inequally of its brightness in different parts may arise 
from unequal condensation or from greater depth of nebulous 
matter. 
II. 313 is “ A pretty bright nebula, a little extended in the 
“ parallel. The greatest brightness is towards the following 
“ side, which is also the broadest ; the preceding part being 
£< more like a ray proceeding from it.” 
The irregular figure of these latter kind of nebulae may be 
admitted to arise from the as yet imperfect concentration of a 
nebulous mass, in which the preponderating matter of it is not 
in the center. 
1 9. Of Nebula that are gradually a little brighter in the ? middle . 
The investigation of the form of the nebulous matter in the 
13, 14, 15, and 16th articles has been founded only upon the 
observed figure of nebulae ; and in the 17th article the globular 
form of this matter deduced from the round appearance of 
nebulae, has been ascribed to the action of the gravitating prin- 
ciple. I am now entering upon an examination of nebulse of 
which, besides their figure, I have also recorded the different 
degrees of light, and the situation of the greatest brightness 
h 5 5 > 313. 33 2 > 3 6 4> 3 37°> 44 2 > 5 o6 > 53 1 * 555’ 5 8 9 > 6z 3* IIL lzo > * 53 > 286 ’ 
676, 700. V. 22. 
