299 
relating to the Construction of the Heavens. 
and the regularity of their figure are both greatly in favour 
of a conclusion, that the mass of the nebulous matter which 
occasions their appearance must be of a globular form. 
In the last article I have only directed our attention to the 
cause of this very particular construction, but from the obser- 
vations of the nebulas above referred to, we may now more 
confidently assign the attraction of gravitation as the principle 
which has drawn the nebulous matter towards a center, and 
collected it into a spherical compass. 
I have already shewn that the same principle appears to be 
the cause of the condensation of the nebulous matter in the 
bright places of nebulae that shine with unequal degrees of 
light in the different parts of their extent,* and a concurrence 
of arguments established upon very different foundations can- 
not fail to give additional weight to the reasonings by which 
they are supoprted. 
18. Of Nebula that are remarkable for some particularity in Figure 
or Brightness. 
Among the nebulas, which I have described as of an irre- 
gular figure, the following might have been inserted; but the 
real form of the nebulous matter of which they consist is pro- 
bably as irregular as the figure or brightness of the nebulas 
themselves. I have arranged thirty-five of them into three 
assortments, •f' 
* See Article 7. 
f See two nebula of remarkable figure. I. 286. V. 19, 
Ten unequally bright nebula. I. 254. II. 200, 210, 422, 557, 591, 646. III. 142, 
245 ’ 534 - 
Twenty. three nebula that are brightest on one side. I. 113, 162. II, 26, 27, 135* 
Qq 2 
