C 3^<^ ] 
Aperture C D admits only the projeftloii G H'^ but G H 
is lefs then wherefore a leffer Aperture, diminiflies 
the projeftion. I admire that any Man that undertooke 
( as Honor am Faber) to write of Opticksmore accurately 
then all that went before him, fhould be guilty of lb very 
grofs an Error; and I do more admire that the Celebrated 
G^/^/^^^y, and with him the Nohk Hevel/us fhould be of 
the fame Opinion ; for tho the forefaid Figure and Demon- 
ftration hold moft certainly true in dired projeftions, as 
in a dark Room with a plain Holej yet it will not hold in 
Projeftions made by Refradion, as it is in thofe on the 
Retina m the Eye, by means of the Qryfidline and other 
Goats and Humours of the Eye. For a Demonftration of 
this obferve the ^/^/V^ F/^. wherein lett ^ jB be a Remote 
Obje£t, and £ JFthe Cry ft dine at its large aperture, pro- 
jecting the Image /Mon the Retina. Let then C D be the 
lelTer Aperture of the Pufil before the Cryftalline: I fay the 
Image /Mfhall be proje£ted as large as before, for the 
Cone of Rays £ ^F coirfifts partly of the Cone of Rays 
CJDy therefore -where the farmer £-^-Fis Projefted, 
riie latter C J D,as being a part of the former, fliall be pro- 
jected alfo. So that no more is effefted by this narrow 
Aperture, but that the fides of the Radiating Cones are 
intercepted, and confequently the Point /lliall be affefled 
with lefs light, but it fhall ftill be in the fame place : 
what isfaid ofthat Cone and that Point may be faid of 
all other Cones and otter Points of the Objeft. From 
lience appears firft, the Invalidity of the Account given 
of the Moons appearance by Gajfendm from this Reafbn ; 
2i^.The Reafon appears why a Telefcopes greater or lefTer 
Aperture, makes no difference in the Angle it receives: for 
imagine E F to be an Objeft^Glafs of a Telefcope, and t^is 
plain, ^/j, 'Tis Evident why a greater or lefs Aperture 
on a Telefcope fhould make the Objefls appear Lighter 
or Darker, for thereby more or lefs Rays are admited to 
determine on the Projection of each Point. But all this; . 
by- 
