Dr. Herschel’s Astronomical Observations 
IV. 64, is <f A beautiful planetary nebula of a considerable 
“ degree of brightness, but not very well denned, about 12 
i( or 15" in diameter.” 
The remarks which have been made on the nebulae of the 
foregoing article, will here apply with additional propriety ; 
for the light of these planetary nebulae must be considerably 
more condensed than that of the foregoing sets. The diameter 
of four of them does not exceed 15," so that if we again sup- 
pose the original diffused nebulosity from which they sprang 
of 10' in cubical dimensions, we shall have a condensation, 
which has reduced the nebulous matter to less than the one- 
hundred and twenty-two thousandth part of its former bulk. 
One of them, number 34 in the 4th class, appeared even in 
the 20 feet telescope, with the sweeping power, like a star 
with a large diameter, and it was only when magnified 240 
times that it resembled a small planetary nebula ; nor can any 
of these nebulae be distinguished from the neighbouring small 
stars in a good common telescope, night glass, or finder. 
When we reflect upon these circumstances, we may con- 
ceive that, perhaps in progress of time these nebulae which are 
already in such a state of compression, may be still farther 
condensed so as actually to become stars. 
It may be thought that solid bodies, such as we suppose the 
stars to be from the analogy of their light with that of our sun 
when seen at the distance of the stars, can hardly be formed 
from a condensation of nebulous matter ; but if the immensity 
of it required to fill a cubical space, which will measure ten 
minutes when seen at the distance of a star of the 8th or 9th 
magnitude, is well considered, and properly compared with 
the very small angle our sun would subtend at the same 
