of the Sun and Fixed Stars. 231 
tween each of thefe ftars as there is between the Sun and Si- 
rius, we muft place thefe clufters 42104 times as far from 
us as that flar is from the fun. But, in order to bring down 
the luftre of Sirius to that of an equal ftar placed at fuch a 
diftance, I ought to reduce the aperture of my 20-feet tele- 
{cope to lefs than the two-and-twenty ce part of an 
inch; when certainly I could no longer expect to fee any 
ftar at all. 
The fame remark may be made with regard to the number 
of very clofe double ftars, whofe apparent diameters being 
alike, and not very fmall, do not indicate any very great mu- 
tual diftance: from which, however, muft be deducted all - 
thofe where the different diftances may be compenfated by 
the real difference in their refpective magnitudes. 
. To what has been faid may be added, that, in fome parts 
of the milky way, where yet the ftars are not very fmall, 
they are fo crowded, that in the year 1792, Aug. 22, I 
found by the gages that, in 41 minutes of time, no lefs than 
258 thoufand of them: had paffed through the field of view 
of my telefcope *. 
It feems, therefore, upon the whole, not improbable that, 
in many cafes, ftars are united in fuch clofe fyftems as not to 
Jeave much room for the orbits of planets or comets; and 
that confequently, upon this account alfo, many ftars, unlefs 
* The ftar-gages ran thus: 
From 19" 35/to 19" 5x! 600 ftars in the field 
19 51—19 57 440 
19 57-20 12 360 
20 12—-20 16 260 
. The breadth of the fweep was 2° 35’, the diameter of the field 15’, and 
the mean polar diftance 73° 54’. Then let 
F, be the diameter of the field of view, 
$, the number of ftars in each field, 
B, the breadth of the fweep, plus F, 
T, the length of the fweep, exprefled in minutes of fpace, 
¢ the fine of the mean polar diftance, 
C, the conftant fraétion ,7854, 
and the ftars in thefe four fucceffive fhort fweeps will be found by the 
BTS¢ Bi , 
expreffion aC equal to 133095. 36601. 74566. 14419. or in all 258981. 
We 
