U t)r. Her schel’s Obfervations 
minutes preceding the 46 Eridani, ftrong, milky nebulofity is 
expanded over more than two fquare degrees. 54' preceding 
the 13th Canum venaticorum, and again 48' preceding the 
fame ftar, 1 found the field of view affedled with whitifh 
nebulofity throughout the whole breadth of the fweep, which 
was 2 0 39". 4' following the 57 Cygni, a confiderablc fpace 
is filled with faint, milky nebulofity, which is pretty bright in 
force places, and contains the 37th nebula of my Vth clafs, in 
the brighteft part of it. In the neighbourhood of the 44th 
Pifcium, very faint nebulofity appears to be diffufed over more 
than 9 iquare degrees of the heavens. Now, all thefe phe- 
nomena, as we have already feen, will admit of a much 
eafier explanation by a luminous fluid than by ftars at an 
immenfe diftance. 
The nature of planetary nebula, which has hitherto been 
involved in much darknefs, may now be explained with fome 
degree ot fatisfadlion, fince the Uniform and very confiderable 
bnghtnefs of their apparent difk accords remarkably well with 
a much condenfed, luminous fluid ; whereas to fuppole them 
to confift of cluttering ftars will not fo completely account for 
the milkinefs or foft tint of their light, to produce which it 
would be required that the condenfation of the ftars ftiould be 
carried to an almoft inconceivable degree of accumulation. 
The furmife of the regeneration of ftars, by means of pla- 
netary nebuhe, exprefied in a former Paper, will become more 
probable, as all the luminous matter contained in one of them, 
when gathered together into a body of the fize of a ftar, would 
have nearly fuch a quantity of light as we find the planetary 
nebula to give. To prove this experimentally, we may view 
them with a telefcope that does not magnify fufficiently to 
fliew their extent^ by which means we fhall gather all their 
light 
