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Show 0/ Seeing. sour. Book Ill. 0f $691255" & ‘ ,T true perception of the viliblc Obit-6t in its proper place, which could not he And it may be alfo proved, that the Ray, (coming from .1 vifible point}- cili-c‘ted ii the Retina was cndued with a greater degree oi iarity. of l, ight being emitted from any vrlible pornt, ( till the chief} The rays A ,chn} mama] an APPUHC - upon the (Retina, i ‘ ' of T blglit) V ' the fiibycc‘t are concewedt0 is firfl refracted in the Cornea, and afterward is variouilv inflected in the urn; be Five in number; as the Rays receive various Relrac'tions in the dilfcrem Tuniclcs and Humors of the Eye, qualified With feveral degrees of Rarity of the Ray is feared in the Retina, in which it terminates and by it theob- and Denfiry. madein the feveral Coats and Humors of the Eye, as f0 many different Me; diums, do dii'tort it, which is regulated by the Retina, as it exceedeth the vitreous Humor in Denfity, vvhcreby it bringeth the Ray to a perpendicu- ,l l' I" iii» amid 1H: .1", 1‘ ‘3" if"? "3"" T " yin [h 4 'i he [hit Ray is carried from the Object through the Air, in right lines to the Cort/m. The Second is refracted by making Angles in the (mm, to. ward the perpendicular. The Third vifible Line (patling‘through the coat ofthc (mica, is infleéted in the \vati'y Humor) recedeth from the Perpen. dicular. The Fourth luc1d Ray being trayecied through the warty Humor, iiiliicreth a Refraction inthe Crifialline, and maketh an Angle toward the Perpendicular: And the Fifth Ray is madein the Retina, as fome will have it, in a right line, and others in an Angular. All Rays, by whofe mediation any vifible point is tranhnitted into the Or. cording to their diH‘erent Rarity and Denlity ; and the mod figiiifimntipart ice? is reduced into aduc order, by reafon the Refraétions ofthe vifible Ray 131', and refioreth the faid Ray to its proper iituation, whereby the viiiblc Objeé‘t is perceived according to its true Figure and Colour, as they are found in nature. And the excellent Fabrick of the Eye giveth a farther confirmation to this Hypothefisa that the molt chief part of the Ray relating: to Sight, may be truly attributed to the Retina; whereupon it happens, that a vil'iblc Oli- jec} being diffufed through the Hemifplimre, lhould be containcdat one vierv nan ofSigl‘t, are called Vifory, of which foiue are lcfs iiifirumcntal, lecon- in the compafs of f0 fmall a Pupil, and afterward be tranlinitted to the Re- dary, and intermedial, and others principal and formal, as araycd with Vifiblc tina, which is accomplifhed by various Refraétions (inadein feveral Membranes and Humors, as al'ti'éted with a more or lefs rare fiibfiance) which are shifted by a due configuration of different parts, and their little fituation in reference to each other, left the more faint vifible Rays, {hould be Images, limiting Appulfes upon the immediate Organ of Vilion. And this propriety may be attributed to the extremity of .1 Vifory Ray that it is not formally an indivifible point, but endued \vith fume li'nfihlt Dimenfions, vrhich may be proved by this argument; That fceing the Line (by \\ hich the Sight is acted ) is not mccrly Mathematical, as it hath breadth as \n ell as length, and by Analogy the chief part ofthe Ray being the terurination of the Line, innit in fome fort participate the fame Dinienlions . with the reft ofthe Line. 1‘" WW" , Another Reafon may be afiigned, that the Vifory Ray doth not terminate m" UV; Crifialline, and Vitreous Humor, to and from the perpendicular ac- confounded by the more liroug beams of Light, dcfiruftive of the Senfe. That the femblances of vifiblc objects may be more clearly and difiinc‘t‘ Howrhcvit , of the Vitreous ~ . . , . r H u: ly perceived,thc largcnefs Humor doth very much contribute, $123,237,, by WhOfC afliflance, the common COHCOUYfC 0f refracted Rays are fo regula- w 5‘3"!ted in the Crifialline Humor, that they may he more finely painted in the Rem" ‘ into an imaginary point, but a fmall Phyfical Body, elfc it is not any Way And moreover, the Figure 0f thC Criftalline Humor, and its m0ti0n for-' 11233110"? il‘miitiilf but capable to make a f'ti'oke upon the Fibrils oi the optick Nerves7 implanted point. into the Tunicle of the (Retina. Whereupon it cannot be difcerncd bytlie Ward and backward, acted by the Ciliary Procefles, doth not only make the :hccniifiiinc Crilialline Humor t0 be more or lefs difiant from the vitreous Humor, bUt iiiifcoliiiirc Organ of Sight, unlels it be afi‘eé‘ted with Breadth and Length, whichatcompany all fenfible Bodies, though never fo minute. giveth a different configuration to the faid Humor, and maketh fornewhat mm" "m" fitting Appulfes of the vifible Rays upon the Retina, and the more clear painting of the images of things upon the faid Coat 3 which maybe rcndred evrdent in the fmall Sphzeresof Glafs,tefembling the Cril'calline Humor of the ly and di‘ltinc'tly difcerning the object (after many Refractions have been Eye; f0 that if a Glafs (like a Face in Figure) be placed near a fmall hole, madcin different parts of the Eye) according to its-true Figure, Colour and Situation. (through which the vilible Rays being tranfmitted from without to an oppo‘ lite White Paper , put in an obfcure place) not only the Situation and Figure of External objects , but their Colours too may be plainly 3:612:13: _\'\'hereforc (lhumbly conceive) it moi} agreeable to reafon, thatthe "UP" 0 E2, chiefpartot the Vilory Ray is feated in the Retina, in which the Ray doth "5:5" terminate, and uiaketh the ultimate Appulfe upon its moft tender Surface, ['5' let with numerous Fibrils (coming iron] the optick Nerve) and inferred-into the Retina, as being an Expanfion, made up of'many nervous Plexc‘t and Branches, by which the firokes of the Vifory Rays are difcerned in the Eyfi and conveyed by the optick Nerves to the inward Senfory of the Brain. ‘ of alteration in the Tunicle of the Retina, and the Cril'talline Humor much "TIE? pm- Conducerh to the variety of Refraétions, and to the making of more or leis The iincis properly and formally ftyled Vifory (by which the SemhlanCes ofthings are perceived) and is radicated in that part ofthe Eye, in which the act of Seeing is principally exerted, and other Tunicles and HUIDOFS are lublcrvrcnt to it, as the ultimate and immediate inf'trument of Sight, clear- Theft: fruitful Fibrils, lodged in the Retina, and derived from the Optic "mush f Nerves, are not propagated through the Vitreous, Criftalline, and was") [him humor into the other coats of the Eye, f0 that they cannot be fenlible of ‘h‘ Appulfes7 made upon their Fibres (by the Vifory Ray) which hold no in- ' timate communion with the opticlt Nerves, as being not cotinued to them by the mediation of any Fibrils. And difcovered after fuch a manner, that no Artift can paint them with fo‘ much life and Elegancy. . . If :1 Chamber can be tendred f0 cIofe, that onlya little or no entrance of "Obi"? Light may be admitted; and a fmall perforation being made, wliofe Diame- iiiiiiiihiig ter is the latitude of 2. Finger more or lefs ( as it may be contrived by an 2215;121:735: Artil't, aceording to the nature of the thing, and its proper ufe) f0 that the "1mm" hole may give a reception to Light, and the vifible Images of things (adorned with their lively colours) feared without the circumference of the hole, which may be tried by placing a White Paper at a due dif'tance, which is raflier difcerned by Experience, then prefcribed by Reafon, and is ordinarily contained Within two or three Spanns of the hole, near which, ifa Glafs ( endued with a Convex Surface) be placed, the Colours clorhed with Light 53mg |