ff. Concerning the Dijiance of the /fixed Stars. 
By the Eonomabk Francis Roberts, Eff^ S.RS. 
TH E Ancient AftrooomerSj who had no other 
way of Computing the Diftancesof the Heavenly 
Bodies but by their Parallax to the Semidianieter of the 
Earth, and being never able to difcover any in the fixe 
Stars, did from thenc€ rightly enough infer, that their 
Diftance was very great, and much exceeding that of 
the Planets, but could go no farther otherwife than by 
uncertain guefs. 
Since the Pythagorean Syftem of the World has been 
revived by Copernicus^ (and now by all Mathematicians 
accepted for the tmt one) there feemed ground to ima« 
gine that the Diameter of the Earth s Annual Courfe 
(which according to our beft Aftronomers is at leaft 
40000 times bigger than the Semidiaraeter of the Earth) 
might give a fenfible Parallax to the fixt Siars, though 
the other could not, and thereby determine their Di- 
ftance more precilely. 
But though we have a Foundation to build on fb vaftly 
exceeding that of the Ancients, there are fome Confide- 
rations may make us fufpeft that even this is not large 
enough for our purpoft, 
Monfieur Hugens (who is very exaft in his Aftrono- 
micalObfervations) tells us, he couU never difcover 
any vitible Magnitude in the fixt Stars, though he ufed 
Glafles which Magnifie the apparent Diameter above 
ICO times. 
t 'ow, fince in all likelihood the fixt Stars are Suns j 
(perhaps of a different Magnitude) we may as a rea^ 
fonable Medium prefume they are generally about the 
bignefs of our Sun. 
Let . 
