C 333 ] 
Sun and Venus at Rodrigues =: g' 2i 7 , 4. Suppo- 
sing then this meafurement to be exadt, here follows 
an irrefragable argument, independent of all other 
methods, to prove that the parallax of the Sun is 
very nearly — 8", 5. Let us fuppofe the Sun’s pa- 
rallax — io y/ , and let us compute, by the following 
method, the apparent lead; diftance of the centers at 
Tobolfkj from thence we fhall find that the geo- 
centric lead didance of the centers at Toboldc is 
56 j ,4^6, and by the oblervation at Rodrigues the 
geocentric lead didance of the centers is = 572", 6-12, 
io that, on this fuppofition, we have two different 
geocentric lead didances of the centers, which be- 
ing ablurd, it follows that the Sun’s parallax is not 
io . Again let us fuppofe that the Sun’s parallax 
is — 7", we fhall find that the geocentric lead dif- 
tance of the centers by the obfervation at Tobolfk 
— 57 5 " > 35^> and by the obfervation at Rod- 
ligues it is 56 g", 248. Thus then, again, we 
have two different geocentric lead didances of the 
centers, which being abfurd, it follows that the pa- 
rallax of the Sun is not '• Again if we fuppofe 
the Sun’s parallax = 8" or 9", we fhall find that 
the fame abfurdity will follow, but in thefe two lad 
fuppofitions we fir all find that the differences of the 
geocentric lead didances of the centers are not fo great 
as on the fuppofitions of 10" and 7", it therefore 
follows that the parallax of the Sun is lefs than 9" 
and more than 8, and if we continue to reafon in the 
fame manner we fhall find, that on the fuppofition 
that the Sun’s parallax is — 8", 5, the geocentric lead 
didances of the centers feverally found by the obfer- 
\ol. LlII. Xx vation 
