■ r . Aft . \ 
> • - , . . ft\" V I 
266 Mr. Herschel on the Conjtruiiion of the Heavens. 
fit for their former purpcfes, and having their projectile forces, 
if any fuch they had, retarded in each others atmofphere, may 
ruin at laft together, and either in iucceftion, or by one general 
tremendous fhock, unite into a new body. Perhaps the ex- 
traordinary and fudden blaze of a new ftar in Cafiiopea’s chair, 
in 157 2, might pofiibly be of fuch a nature* But left I Ihould 
be led too far from the path of obfervation, to which I am 
refolved to limit myfelf, 1 (hall only point out a confiderable 
Tile that may be made of thefie curious bodies. If a little atten- 
tion to them fhould prove that, having no annual parallax, they 
belong moft probably to the clafs of nebulae, they may then 
be expected to keep their fituation better than any one of the 
ftars belonging to our fyftem, on account of their being pro- 
bably at a very great diftance. Now to have a fixed point 
fomewhere in the heavens, to which the motions ol the reft 
may be referred, is certainly of confiderable confequence in 
Aftronomy ; and both thefe bodies are bright and fma -11 enough 
to anfwer that end (fi). 
Datchet near Windfor, W. HERSCHEL. 
January r, 1785. 
(b) Having found two more of thefe curious objedls, I add the place of them 
here, in hopes that thofe who have fixed inftruments may be induced to take an 
early opportunity of obferviug them carefully. 
Feb. I, 1785. A very bright, planetary nebula, about half a minute in diame- 
ter but the edges are not very well defined. It is perfectly round, or perhaps a 
very little elliptical, and all over of an uniform brightness : with higher powers 
it becomes proportionally magnified. It follows y Eridani 16 16 in time,, and 
is 4<y more north than that fiar. 
Feb. 7, 1785. A beautiful, very brilliant globe of light; a little hazy on the 
edges, but. the hazinefs goes off very fuddenly, fo as not to exceed the 2Qth part 
of the diameter, which I fuppofe to be from 30 to /\.o . It is round, 01 perhaps 
a very little elliptical, and all over of an uniform brightnefs : I fuppofe the intenfity 
of its light to be equal to that of a fiar of the ninth magnitude. It precedes the 
third b (Fl. 6.) Crateris 28' 36" in time, and is i° 25' more north than that fiar. 
