Difiance, Magnitude, &c. of the Fixed Stars, &c. 55 
thefe groups. Now. of the ars which we.there fee collected 
together, it is highly probable, as I have obferved in that paper, 
that there is not one in.a hundred which does not belong to the 
group itfelf; and by far the greateft part, therefore, according 
to the fame idea, muft lye within a {phere, a great circle of 
which is of the fame fize with a circle, which appears\to. us. 
to mcelude the whole. group.. If we fuppofe,. therefore, this. 
ivcle.to be about: 2”.. in diameter, and confequently only about 
a sc aa part of the diftance at which it is feen, we may 
conclude, with the higheft degree of probability, that by. far 
the greateft part of thefe ftars do. not ‘differ in their diftances 
from. the fun. by more,than about one part in. thirty, and- from 
thence deduce a fort of {cale of the. proportion. of the light 
which is produced by different, ftars. of the fame group or fyftem 
in the Pleiades at leaft; and, by a fomewhat probable analogy,,: 
we may do the fame, in other fyftems likewife. But. having: 
yet, no means; of. knowing their real. diftance, or {pecific bright- 
ne{s, when compared either with the fun, or’ with one another,.. 
we fhall fill, want ididiasibhas more to. form: a. ofenihet neers 
from. 
38 1 a Rei it fieuld ; be. found,, that Sak ree 
Pleiades, or any other like fyftem, cheseare fome ftars chat are: 
double, triple, &c. of which oneis a larger central body,. with 
one or more fatellites revolving about it, and the central body 
fhould likewife be found to diminifh the velocity of its. light ;:: 
and more efpecially, if there: fhould be feveral fuch inftances 
met with in the fame fy{tern ;, we fhould then begin to have a 
kind of, meafure-both of the diftance of fuch a fyftem of ftars. 
from the earth, and of their mutual diftances from each other.. 
And if feveral inftances of this kind fhould occur in different 
groups or fyftems of ftars, we might alfo, perhaps, begin to 
x form 
