258 Mr. Herschel on the 
draggling ftars of courfe will be very few in number ; and 
therefore the ground of the heavens will ail u me that purity 
which 1 have always obferved to take place in thofe regions. 
Enumeration of very compound Nebula or Milky -Ways. 
As we are ufed to call the appearance of the heavens, where 
it is furrounded with a bright zone, the Milky- Way, it may 
not be amifs to point out home other very remarkable Nebulas 
which cannot well be lefs, but are probably much larger than 
our own fyftem ; and, being alfo extended, the inhabitants of 
the planets that attend the ftars which compofe them mull 
likewife perceive the fame phenomena. For which reafon they 
may alfo be called milky-ways by way of diftin&ion. 
My opinion of their fize is grounded on the following ob- 
fervations. There are many round nebulae, of the firih form, 
of about five or fix minutes in diameter, the fiars of which I 
can fee very diftin&ly ; and on comparing them with the vifual 
ray calculated from fome of my long gages, I fuppofe,by the ap- 
pearanceofthe fmall ftars in thofe gages, that the centers of thefe 
round nebulae may be 600 times the diftance of Sirius from us. 
In eftimating the diftance of fuch duffers I confulted 
rather the comparatively apparent fize of the ftars than 
their mutual diftance % for the condenfation in thefe elufters 
being probably much greater than in our own fyftem, if we 
were to overlook this circumftance and calculate by their appa- 
rent compreffion, where, in about fix minutes diameter, there 
are perhaps ten or more ftars in the line of meafures, we fhould 
find, that on the fuppofition of an equal fcattering of the ftars 
throughout all nebula, the diftance of the center of fuch a 
duller from us could not be lefs than 6000 times the diftance 
of 
