( 6 i) 
parrying them, if they perform no more, than fhorter ones. 
\ Where, by the by, he cakes notice, that he knows not yet, what 
Aperture Signor Campani gives to his Glaffes, feeing he hath as 
j yet lignified nothing of it ; but that the fmalLone, fent by him 
to Cardinal Antonio , hath no more Aperture ) than ordinary ones 
ought to have. 
He promifes withal! , that he will explicate this way in his 
Treatife of the ufefulnefs of Telef copes , where he intends to aflign 
the Bignefs of the Diameter of all the Planets , and their propor- 
tion to that of the Sun ; as alfo, that of the Stars j which he e- 
fteems yet much lefs, than all thofe have done, that have writ- 
ten of it hitherto ; not believing, that the Great Dog , which ap- 
pears to be the faireft Star of the Firmament , hath i Seconds in 
i Diameter , nor that thofe, which are counted of the fixth Mag- 
nitude, have 20 thirds 5 nor thinking, that all the Stars, that are 
in the firmament, do enlighten the Earth as much as a Luminous 
Body of 20 [econds in Diameter would do, or, becaufe there is 
but one half of them at the fame time above our Horizon, as a 
Body of 14 feeondsm Diameter • and as the 18432 th part of the 
Sun would enlighten us, or as the Sun would do, if we were 14 
times more diftant from it. than Saturn, and 137 times further, 
than the Earth: Which, he faith , would not be credible, if he 
did not endeavor to evince it both by Experience and Tfeafon. 
And he doubts not, but that Venus , although file fends us no 
Light but what is reflected, does fometimes enlighten the Earth 
more, than all the Stars together. Yet he would not have us i- 
magine,from what he bath fpoken of the finalnefs of the Stars, 
that Telefopes do not magnifie them by reafon of their great di- 
ftance, as they do Planets ; for this he judgeth a Vulgar Error, 
to be renounced. Telefcopes magnifie the^f^r/ (faith he*) as 
much in proportion, as they do all other Bodies, feeing that the 
demonftration of their magnifying is made even upon Parallel 
rays, which do fuppofe an infinite diftance , though the Stars 
have none fuch : And if the Telefcopes did not magnifie the Stars, 
how could they make us fee fome of the fiftieth , and it may 
befome of thchundreth, and two hundreth*Magnitude , as they 
do., and as they would fhew yet much lelfer ones , if they did 
magnifie more ? 
z 
Mr. 
