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Show ' P ‘BOOliITI: 882. W, l iOf‘ the Eyes". r. K away" It is generally conCCiVed that Clafs and Precious Stones have one uniform inward Conipage; but upona curious furvey, they may be plainly difcovered to be fyltems made up of many thin Flakes, f0 neatly c?")°)‘"¢d, that they may well impole upon a naked Eye carelefcly Viewing the." clole Cominillures: But if you hold .up fame very thin clear (alafs agamf} the Light, 16 thatthel'lateit felf is lcarce dilcernible by a negligent eye, and: more curious perfon cannot be brought to conceive that a thin plate of Glafs may be divided into many Laminar, which though it be contrary to the vulgar opinion, yet it hath been experimented by followmg the Grain oftht . . Clafs that it may be fplit into many fine Plates. Tricnpmc- And I conceive this Hypothefis may be farther proved, by diligent infpe. i,i",3,]tiiiiiics fiion of Precious Stones, decked with Geometrical Figures, [cared in fome 51"" parts of their furfaces, wherein With'a quick Eye, may be dilcovered many parallel Commifliires, fhewiiig themfelves in many contiguous edges of minute thin Plates, which feem to lie one over another, like the Leaves of; . ‘ . . Book a little opened. And alfo in Saphires and Hyacinths, it is pollible to efpy (by turning them divers ways to the Light) the fine conyunétions of the Flakes, and I conceive thcfe Precious Stones will admit a fplitting according to the Dué‘ts of that Grain, which is commonly done by Artifis in Diamonds, whole Lam", confif't of parallel Plains; but if the Plains of the Plates run counter to each other, the Diamonds cannot be fmoothly fplit, becaufe the Commifliires go unequally, making Angles in the body of the Stone; Which I conceive , render the compage of the Diamond lels Tranfparent and foul (whereupon it is judged no Paragon) as intercepting the free difplaying of the beams of Light within the crofs Grains, and unequal run. ning of the Commillures of the Plates. Thus I have attempted to give an account of the nature of Glafs, Crilial, and Gemms in their full: produéiion in Solidi/5 principiis as Fluid Bodies, and in their greater maturity of more folid Compage (concre- ted by fine faline and earthy Particles) made up of many thin Flakes, in which they hold a great analogy with the Cornea, and do illuftrate the origen of its Tranfparency in a Fluid Subftance, compounded in a multitude of Atoms, inrerfperfed with innumerable minute Spaces; whereupon the mofi finall parts of Seminal Liquor, out of which the Comm is originally formed, may be eafily diflbciated, and put upon motion from term to term, as it confif'teth of f0 many active Atoms, iiitei'lai'ded with many minute Interf'tices, filled With WM", thinner fubl‘tances (every way reitgnivc of Light) the firfl rudiment $3;an of Tranfparency in the Cornea, wherein the tranfmiflion 8% Rays pfifi runny. every where through its porous Compage (when it is Fluid) fothaf the current made by pervious impreflions are afterward retained, when the Cornea is coagulated into divers thin Flakes, as fo many faline ACCT? tions, curioufly conjoyned, whereupon the numerous rOWS of Parallel Plains‘ and Surfaces (as every thin Flake hath an upper and lower Surface} are united in fine Commifliires, into whofe innumerable minute Pores» Book III. 0f the Ej'é'J'. The next Tunicle of the Eye hath the Appellative of term: by the Geeky and "ma 1* and Twin: irwiformir by the Latinas", as being like in colour 1-, mm," to the Stone of aGrape 5 butI humbly conceive that it hath ecceived this dea iiiihh'rim nomination, rather from its orbicular Skin, as a Velicle, encircling a tranll Ei'e.‘ca'l1:d'" parent Liquor, not much unlike that of the aqueous Humor of the Eye; DWI By orhers this Membrane is called Maxim, as rfilemblingthe Corion in the divarications of Arteries and Veins, finely enameling this Coat ; which ran keth its rife from the rPia Mater, and encompaffeth the whole circumference of the Eye, and its upper region is for the molt part affixed to the Sclernlica by the interpolition of many finall Arteries, Veins, and Lioaments or ta: ther thin Membranes. D D Its inner Surface is fupported by Swimming upon the aqueous Liquor to This" 5 which it is contiguous in its Concave Surface, and to the Sclerotira iii its the em. Convexe, and is of an orbicular Figure, as fitly complying with the round Figure of the ambient parts. Its inward Surface is beautified with one entire uniform colour, being Black in Men, Yellow in Cats, and Sky-coloured in Bullocks. The neighbouring Membrane is called Iris, a1) Iridir Celeflis/imilimdim as TthunTcle it is painted in its anterior Region ( Where it is loofe in reference to motihn) "Pf?" with great variety of colours, fometimes Black and Hafle, and other times a": "TA" Blew, Green, Sky-coloured; to that its outfide is airy and oay, but its in""010". fide hath a more fober drefs of Sables, as hung with Black, Iraendririg all the inward chambers of the Eye dark (rightly conl'cituted by the All-wife Agent ) that the vifible refemblances being clothed with the bright Rays of Light, mightnot confound the Senfe with their over-much fplendor; and to that end the Beams of Light (invefiing theoutward objeéts) receive a. due allay with gloomy Shades in the dark recefles of the Eye, to attemper thisgreatgaynefs, before they make Appulfes upon the tender Organ of Sight. This Membrane is a part of the Choroides, but according to Kiolm itis a adifiinét Membrane, and may be feParated, as the Author faith, from the More, which he found in the boiled Eye ofa Beafl; but all other Anatomil ts are of a different judgment, holding the Iris robe one continued part with the Mom, to which it is {0 firmly annexed, that they cannot be fevered from each other, without offering a great violation to them : And the Iris, though It fpringeth out of the Choroides, as being one entire part with it, and is feated under the Cornea, yet it is not like to it, and Homocentrical with it, but is different from the Mara, and all other Membranes of the Eye, which are whole, and entire Segments of their orbiculat Surfaces 5 but the Iris bemg perforated in its Center, repreléntetha fmall Ring or Circle, through which the vifible Images of things arrayed with beams of Light, are darted 312:0. the tranfparent humors ofthe Eye, and at lafl; make Appull‘t‘s upon the mm. .The Pupil ofthe Eye 1- is a Perforation drilled through the middle of 1m, and is oblong, or oval in Brutes, but orbicular in Mean, making the $13553? a lit- ""EYC- tle Circle about the Center ofthe greater Circle of the Iris, and is merited the fubtle Ethereal Particles of Light may eafily infinuate , and freely difplay themfelves, giving that pleafant tranfparency to the Carma, 35 well as to Glafs, CriflalJ Gems, and other Diaphanous Bodies, With various obfcuie motions, whereby it is gently dilated and contraéte d, according to the reception ofythe fainter, or brighter Rays of Light. " The Pupil is 'fitpported, as floating upon the watry Humor ofthe Eye, and The dy places, endear y in the Morning, and late in the Evening, wherein the Pupil is dilated to give a freer reception to the more obfcure beams of Light; Is enlarged asit ap roacheth nearer to the Cornea, which is occalioned in {liaa R 10 And |