C 2 4 2 1 
light. Now, according to the bed judgment I have 
been able to make from fome grofs experiments, the 
quantity of light which we receive from Sirius does 
not exceed the light which we receive from the lead 
fixed flars of the fixth magnitude in a greater pro- 
portion than that of 1000 to i, nor in a lefs propor- 
tion than that of 400 to 1 ; and the fmaller flars of 
the fecond magnitude feem to be about a mean pro- 
portional between the two. Hence the whole par- 
allax of the lead fixed dars of the fixth magnitude, 
fuppofing them of the fame fize and native brightnefs 
with the Sun, fhould be from about 'i" r to 3'", and 
their didance from about eight to twelve million times 
that of the Sun : and the parallax of the fmaller 
flars of the fecond magnitude, upon the fame fup- 
pofition, fhould be about 12"', and their didanc.e 
about two million times that of the Sun. 
I have hitherto argued about the didances of the 
fixed dars, upon the fuppodtion of their being of the 
fame fize and brightnefs with the Sun ; and, if this 
was really fo, thofe which appear the brighted mud 
be the neared to us. That this is in general the cafe, 
I fuppofe, will be very readily allowed; for, though 
it is true, that a much greater degree of real mag- 
nitude may compenfate for the greatnefs of didance, 
and there is no reafon for afiigning any one limit to 
them rather than another; yet, when it is as likely 
that the larged dars diould be in any one part of 
fpace as in any other, the probability in favour of 
this hypothefis is very great : the real motions all'o, 
which have been obferved amongd feveral of the 
brighted of the fixed dars, is another argument to 
the fame purpofe; and we fhall find it dill farther 
confirmed 
