Dr. Herschel’s Astronomical Observations 
'b 
Some part of the nebulous matter is probably elastic, 313 
The uniform light of nuclei, and of much condensed ne- 
bulas, proves that the nebulous matter is considerably 
opaque, 313 
When the nebulous matter assumes hardness, the pro- 
gress of condensation will be impeded, - 314 
Three indications of the compression of the nebulous 
matter, - - - - 31 5 
Planetary appearance arises from superficial lustre, 315 
High degree of condensation of the nebulous matter, 31b 
A still higher degree of condensation, - - 31 6 
In common good telescopes planetary nebulae cannot be 
distinguished from stars, - - - 31S 
Perhaps they may in the end be so condensed as actually 
to become stars, - - - - 318 
The nebulous matter in a cubical space of 10' will admit 
of a condensation of two trillion and 208 thousand 
billion times before it can go into the compass of a 
globe of the diameter of our sun, - - 31 9 
Planetary nebulae have a rotatory motion on their axes, 319 
The original eccentricity of the nebulous matter of a 
nebula may be the physical cause of the rotatory 
motion of celestial bodies, - - - 31 9 
The nebulous star in Orion is fictitious, - 320 
Two out of three nebulous stars in Orion have lost their 
former neb lou.s appearance, - - 321 
Their fictitious appearance was owing to a dispersion of 
their light in passing through nebulous matter, 321 
The faintest appearance of the nebulosity in Orion is 
perhaps not further from us than the stars of the 3d 
