« \ _ 
358 Dr, Herschel's Astronomical Observations 
That such motions may happen has been shewn in the third 
article, which contains instances of the conjunction of stars 
with nebulosities of which they cannot have been formed, and 
which must, consequently, have been united by motion. We 
also know that nebulse are subject to great changes in their 
appearance, which proves that some of the nebulous matter in 
their composition must be in motion; instances of which have 
been given in the luminous nebulosity of the constellation of 
Orion.* It may therefore be easily conceived that any mov- 
ing patch of nebulous matter must be arrested on its meeting 
with stars; especially if several of them should happen to be 
pretty near each other; in which case there will be, as it were, 
a net spread out for intercepting every nebulosity that comes 
within the reach of their attraction. 
II, 304. “ Three or four stars of various sizes are mixed 
“ with pretty strong nebulosity.'" 
III, 165. “ Five or six stars forming a parallelogram, are 
‘‘ mixed with very faint milky nebulosity." 
III, 697. “ Several small stars are contained in faint nebu- 
“ losity about 3 or 4 minutes long and \ broad." See fig. 10. 
IV, 75. “ Three stars of about the 9th or 10th magnitude 
** are involved in pretty strong milky nebulosity." 
This collection of thirty-seven objects, consisting of 2, 3, 4, 
5, 6, or more small stars that are mixed with nebulosity, con- 
tains a variety of instances in which the effect that has been 
mentioned of the interception of the nebulous matter may have 
taken place. It is very obvious that nothing positive can be 
said about the formation of so many starry-nebulous patches; 
for unless by long continued observation of the same patches 
• Phil. Trans, for i8ii, p. 320. 
