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employed in the formation thereof. But the Defi and Skill of the infinite Workman, will beft be fet forth by 6. Surveying the Parts and Mechanism of this admirable Organ the Eye. And here indeed we cannot but stand amazed, when we view its admirable Fabrick, and confider the prodigious exaćtnefs, and the exquisite Skill employed in eve part ministering to this noble and necessàry Senfé.

by affested, and the Soul thereby informed, &c, but fee more hereafter under Note 38, from Cartes himself. Somewhat like this is the Notion of our judicious Dr. Briggs, who thinks the Optick Nerves of each Eye confist of Homologous Fibres, having their rife in the Thalamus Nervorum opticorum, and thence continued to both the Retine, which are made of them : And farther, that thofe Fibrille have the fame Paralleliím, Tenfion, &c. in both Eyes; and consequently when an Image is painted on the fame corresponding, sympathizing Parts of each Retina, the fame Effects are produced, the fame Notice or Information is carried to the Thalamus, and fo imparted to the Soul, or judging Faculty. That there is fuch an 'Oueinioeta between the Retine, &c. he makes very probable from the enfuing of double Vision upon the Interruption of the Parellelism of the Eyes; as when one Eye is depressed with the Finger, or their Symphony interrupted by Difeafē. Drunkennefs, ere. And lafily, that fimple Vision is not made in the former way, viz. by a Decuffation or Conjunĉtion of the Optick Nerves, he proves, because those Nerves are but in few Subjects decuffated, and in none conjoined otherwife than by a bare Contast, which is particularly manifest in Fishes ; and in fome Instances it hath been found, that they have been separated without any double Wifion enfuing thereupon. Vid. Brig. Õphthalmegr. cap. I 1. & ş. and Nov. Vif Theor. passim, What the Opinion of our justiy eminent Sir Isaac Newton is, may be feen in his Opticks, Q. I 5. Are not the Species of Objetis, feen with both Eyes, united where the Optick Nerves meet before they come into the Brain, the Fibres om the right fide of both Merves uniting there, &c. . For the optick Nerves of fuch Animals as look the fame way with both Eyes, (as of Men, Dogs, Sheep, Oxen, &c.) meet before they come into the Brain ; but the optiek Nerves of fuch Animals as do not look the fame way with both Eyes, (as of Fishes and of the chameleon) do not meet, if I am rightly informed. Newt

Opt. Q. 15. To

To país by its Arteries and Weins and fuch other Parts common to the reft of the Body, let us cast our Eye on its Muscles. Thefe weshall find exaćłly and neatly placed for every Motion of the Eye. Let us view'its Tunicks; and thefe we shall find fo admirably feated, fo well adapted, and of fo firma Texture, as to fit every place, to answer every occafion, and to be proof against all common Hnconve. niences, and Annoyances. Letus examine its three Humours ; and these we shall find all of exquistte Clearnefs and Transparency, for an easy Adinistion of the Rays; well :::::: the refraćting of them, and formed (particularly the Crystalline Humour) by the nieeft Laws of Opticks, to collect the wafidering Räys into a Point. And to name no more, let us look into its darkned Cell, where those curious Humours lie, and into which the Glories of the

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ly Pictured; and this Cell we ħalí find, without, well prepared by Means of its Texture, Aperture, and Colour, to fence off all the ufeless, or noxious Rays ; and within, as well coated with a dark Tegument, that it may not reflećt diilipate, or any way confuse, or đifturb the beneficial Rays (16). But to descend to Particulars, although it would be a great Demonftration of the Glory of God, yet would take up too much Time, and hath been in fòme Meafure done by others, that have written of God’s Works. Paffing over therefore what they

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have observed, I shall under each principal Part take a tranfient Notice of fome Things they have omitted, or but flightly spoken of - - And my first Remarkshall be concerning the Muß cles of the Eye, and their Equilibration. . Nothing can be more manifestly an aćt of Contrivance and Defign, than the Muscles of the Eye, admirably adapted to move it any, and every way 5 upwards, downwards, to this fide, or that, or howfoever wé pleafe, or there is occafion for, fo as to always keep that Parallelifin of the Eye, which is necessàry to true Wifion. For the Performance of which Service, the Form, the Position, and the due Strength of each Muscle is admirable. And here I might inflance the peculiar and artificial Strućture of the Trochlearis, and the Augmentation of its Power by the Trochlea (17) ; the Magnitude and Strength of the Attollent Muscle, fomewhat exceeding that of its Antagonift; the peculiar Muscle called the Seventb or Suspensory Muscle (18), given to Brutes, by reafon of the pronePosture of their Bodies, and frequent |- Occa

(17) Admirandum Dei artificium ex diverforum animalium comparatione indies evadit manifestiùs. Mirantur omnes Trochlearem in ceulio Hominum & Quadrupedum, & quidem jure : fed admirationem omnem fuperat, quod fine Trochleå oculum movens in Avibus novum genus Trochlee longè artificiosius Willitandi Membrane dederit. Blaf Anat. Animal p. 2. c. 4. ex Stenon. - [Mufculum Trochlearem] per intermedium trochleam tradustum, nunquam intueor, quin admirabundus mecum, ‘o e às, exclamem, e usvor de Yaoustréi, ixxa è dei uoxarärzt. I. C. Sturmii Exercit. Acad. 9. de Vif. Org. & Rat c. 3. §. 4. p. 446. se (18) observare est quod Quadrupedes, qui oculos in terram pronos, se pendulos gerunt, Mufulum peculiarem habent, quo oculi globus fufpenditur Hoe Mufulo Bos, Equus, Ovis, Lepus, Porcus, &c. prediti funt : hoc etiam Canis infruitur, fed alio modo conformatunz habet: . Willis de An: Brut. p. 1. c. 15. » Of this Opinion alfo was Bartholine Anat. l. 3. c. 8, and divers other eminent Anatomifts.

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ment Muscles. By this fo curious and exaći a Libration, nốt only unfeemly Contortions, and incommodious Vagations of the Eye are prevented, but alfo it is able with great readiness, and exaćtness to apply it felf to every Qbjeći. t.

As to the Tunicks of the Eye, manythings might be taken notice of, the prodigious Fineneß of the Arachnoides, the acute Senfe of the Retina, the delicate Transparency of the Cornea (21), and the firm and strong Texture of that, and the Sclerotica too; and each of them in thefe, and every other respeét in the most accurate manner adapted to the place in which it is, and the Business it is there to perform. But for a Sample, I shall only take notice of that part of the Uvea which makes the Pupil. It hath been observed by others, :::::::: by our Honourable Founder (22), That as we are forced to ufe various Apertures to our optick Glaffès, fòNature hath made a far more compleat Provision in the Eyes of Animals, to shut out too much, and to admit fufficient Light, by the Dilatation and Contraćtion of the Pupil (23). But it deferveth our especial Remark, that thefe Pupils are in divers - - - . . . . i , , Animals

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