308 Dr. Herschel’s Astronomical Observations 
round ones, which can be ascribed only to the continued ac- 
tion of the attracting principle, tending to draw the nebulous 
extended expansion into a globular form. 
A nucleus, to which these nebulae seem to approach, is an 
indication of consolidation ; and should we have reason to con- 
clude that a solid body can be formed of condensed nebulous 
matter, the nature of which has hitherto been chiefly deduced 
from its shining quality, we may possibly be able to view it 
with respect to some other of its properties. 
24. Of round Nebula; increasing gradually in brightness up to a 
Nucleus in the middle. 
It has already been proved, from the figure and central 
brightness of round nebulae, that the nebulous matter of which 
they consist must be admitted to be of a globular form ; but 
the following thirteen nebulas lead me to a remark which not 
only applies to them, but to all the round nebulae of the last 
five articles, which added to these amount to three hundred 
and twenty-one. They are not only round, but the gradual 
condensation from the circumference to the very center being 
of equal density of light at equal central distances, every ring 
or circle drawn round the center, bears witness to the exist- 
ence of a central attraction. For whatever may be the inten- 
sity or ratio of the concentration at any given central distance, 
it follows, from the equality of brightness at the assigned 
distance, that no figure but a globular one can with any kind 
of probability explain the appearance ; and that the concentra- 
tion, as well as the figure, is produced by a general gravitation 
of the nebulous matter.* 
* See I. 2, 6, 132, 15 1, 173, 236, 272. II. 25, 189, 716, 864. III. 518. IV. 6. 
