Mifcettanea, Curio fa. 17 \ 



with a plain' hole j yet it will not hold in 

 Proje&ions made by Refraction, as it is in 

 thofe on the Retina in the Eye, by means of 

 the Cryflalline and other Coats and Humours 

 of the "Eye. For a Demonftration of this ob- 

 fcrve Fig. 43. wherein let A B be a remote 

 Object , and E F the Cryflalline at its large 

 aperture, projecting the Image 1M on the 

 Retina. Let then CD be the letter aperture 

 of the Pupil before the Cryflalline : I fay the 

 Image I M ftiall be proje&ed as large as be- 

 fore, for the Cone of Rays EAF confifts 

 partly of the Cone of Rays C A D, therefore 

 where the former EAF is projected, the 

 latter CAD, as being a part of the former, 

 lhall be projected alfo. So that no more is 

 effected by this narrow Aperture , but that 

 the fides of the radiating Cones are inter- 

 cepted, and confequently the Point I lhall be 

 afFe&ed with lefs light, but it lhall ftill be in 

 the fame place : What is faid of that Cone 

 and that Point may be faid of all other Cones 

 and other Points of the Object. From hence 

 appears firft , the Invalidity of tbe Account 

 given of the Moons appearance by Gajfendm 

 from this Reafon. 2dly, The Reafon ap- 

 pears why a Telefcopes greater or letter 

 Aperture, makes no difference in the Angle 

 it receives ; for imagine EF to be an ObjecV 

 glafs of a Telefcope, and 'tis plain. 3dly, 

 'Tis evident why a greater or lefs Aperture 

 on a Telefcope fhould make the Objects ap- 

 pear Lighter or Darker, for thereby more or 

 lefs Rays are admitted to determine on the 

 Projection of each Point. But all this by the 

 by. And this is fufficient for a Confutation 



of 



