Laftly. the third or immediate Ey^-gUfs does nothing 
towards the ereCling or revcrfing the Species, which it re- 
ceives ereO; from the middle Yje-ghfs ) no more than in a 
Telefcope of two Convex-glaflies, thtV^ycgUfs does to the 
Species it receives from the Ohje^t^gUfs^ as we have fhewn 
before. The reafbn that this laft or immediate 'Eye-gUfs 
has nothing to do in the ere£lirig or reverfing the Species 
is the fame,as ina Teiefcope of two Convex-glaires,'t'/;t;. the 
Eye is placed in its Vocus^ and thei'efore fees the Species as 
'tis reprefented in the Diftm6t Bafe \ that is, the Species 
is inverted in the DiJtin^Bafe of thei)%(^-^/^y5', and there^ 
fore a fingle Convex ^ye-gUjs brings it to the Eye inverted ; 
but in the D//?/;^<^-jS^ of the middle or fecond Eye-gUfs 
the Species is erect, and therefore the third or iramedi« 
ate Eye-glafs brings it to the Eye ereft. 
Wherefore we are to confider the Teiefcope confifting of 
-ginOhjelf-giafs 3.nd thvQQ Eye-g/ajfes, as two Teiefcopes, each 
confifting of two Convex-glafres. The firft confifts of th& 
ObjeB-gUfs and firft Eye^glajsy and this inverts the Species; 
that is, the Species is inverted in the Di/z^i^-jB^/^ of the 
OhjeB-glafsy andib brought into the Eye. The fecond Te- 
iefcope confifts of the two immediate Eye-g/ajfesy and this 
erefts what the fofmer inverted, that is, the Species in the 
Diflmff'Bafe of the middle Eye-gLajfs is ereO: , and is lb 
brought into the Eye by the Eye-gUjs ; the Eye-glajfes them- 
fch-es in neither cafe having any thing to do with the Ci- 
refting or inverting, but meerly in repreienting in the 
feme pofture the Species immediatly before tiiem. 
The French Problem therefore fliouid nor iiave broken a 
Teiefcope of four Convex-gialTes into four peices, but into 
two, and the cafe would have been plain; whereas by break- 
ing itr into four Perfpedive-Glaffes, they attribute that to 
two of them, which neither of them does, viz, inverting 
anderefting. 
Therefore I fay laftly, that one Convex-glafs as pofited 
inaTclelcope inverts, the fecond (that is the firft Eyc-gUfs) 
X 2 ' does 
