Difiance, Magnitude, Sc. of the Fised Stars, Ge. 45 
much too fmall to be obferved by any telefcopes yet exifting, 
or any that it. 1s probably i in the power of human abilities to 
make ; ; for the apparent. diameter of the central ftar, if of the 
fame denfity with the fun, when feen .from another body, 
which would revolve round it in 64 years, would be only the 
17i7th part of the diftance of thofe bodies from each othe ef, ¥As 
will appear from multiplying 107,32, the number of times the. 
fun’s diameter is contained in his pene from:the earth, by 16, 
the greater proportional diftance of the revolving body, cor- 
re{ponding to 64 years inftead of 1. Now the 1717th part of a 
fecond muft be magnified 309.060 times in order to give it an 
apparent diameter of three minutes; and three minutes, if the 
teleicopes were mathematically perfect, and there was no want 
of diftinétnefs in the air, would be but a very tmpall matter to 
Judee at *. : 
, | fiat F 23. But 
* In Mr. Herscuew’s Obfervations upon the Fixed Stars abovementioned, almoft 
all of them arereprefented as appearing with a well-defined round dife. That this 
is not the real dife, but only an optical appearance, occafioned perhaps by the 
conftitution of the eye, when the pencil, by which objeéts are feen, is fo exceed- 
ingly {mall as thofe which he employed upon this occafion, is very manifeft, from 
the obfervations themfelves, of which indeed Mr. Herscuet feems to be himfelf 
fufficiently aware: if it were not fo, the intenfity of the light of thefe flars muft 
‘either be exceedingly inferior indeed to that of the fun, or they muft be immenfely 
larger, otherwife they muft have a very fenfible parallax; for ‘the fun, if removed 
to 10.000.000 times his prefent diftance, would ftill, I apprehend, be of about 
the brightnefs of the ftars of the fixth magnitude; in which cafe he muft be mag- 
nified 1.000.000 times to make his apparent dife of any fenfible magnitude; or, 
on the other hand, if he was only removed to a thoufandth part of that diftance, 
then he muft be lefs luminous in the proportion of 1.c0o0,000 to I, to make him 
appear no brighter than a ftar of the fixth magnitude. Now the fun’s diameter 
being contained nearly 215 times in the diameter of the earth’s orbit, the annual 
parallax therefore of fuch a body in that cafe, if it was placed in the pole of tne 
; ecliptic, 
