For

CHA P. II.

Of the Eye.

OR our clearer Proceeding in the Confideration of this noble Part (a), and understanding its Economy, I fhall confider:

7. The Guard and Security Nature hath provided for this fo useful a Part.

As this eminent Part hath not been pretermitted by Authors, that have made it their particular Defign and Business to speak of the Works of God; fo divers of the aforefaid Particulars have been touched upon by them. And therefore I fhall take

(a) In Diffectionibus anatomicis vix aliquid admirabilius, aut artificiofius ftructurâ Oculi humani, meo quidem judicio, occurrit: ut meritò, per excellentiam, Creatoris appelletur Miraculum. Gul. Fabr. Hildan. Cent. 2. Obferv. 1.

So likewife that accurate Surveyor of the Eye, Dr. Briggs, whofe Ophthalmography I have met with fince my penning this Part of my Survey. His Character of this curious Piece of God's Work is, Inter præcipuas corporis animati partes, que magni Conditoris noftri fapientiam oftendunt, nulla fanè reperitur, quæ majori pompâ elucet quàm ipfe Oculus, aut quæ elegantiori for mà concinnatur. Deum enim aliæ partes vel minori Jatellitio ftipantur, vel in tantam venuftatem haud affurgunt; Ocelli peculiarem honorem & decus à fupremo Numine efflatum referunt, & nunquam non ftupenda fuæ Potentiæ characteres repræfentant. Nulla Jenè pars tam divino artificio ordine, &c. Cap. i. fect. 1.

in as little as poffible of what they have faid, and as near as I can, mention chiefly what they have omitted. And,

1. For the Form of the Eye; which is for the moft part Globous, or fomewhat of the sphæroidal Form, which is far the more commodious optical Form, as being fitteft to contain the Humours within, and to receive the Images of Objects from without (b). Was it a Cube, or of any multangular Form, fome of its Parts would lie too far off (c), and fome too nigh those lenticular Humours, which by their Refractions caufe Vifion. But by means of the Form before-mentioned, the Humours of the Eye are commodiously laid together, to perform their Office of Refraction; and the Retina, and every other

(b) It is a good Reafon Friar Bacon affigns for the Sphæricity of the Eye; Nam fi effet plane figuræ, fpecies rei majoris oculo non poffet cadere perpendiculariter fuper eum — Cùm ergo Осиfus videt magna corpora, ut ferè quartam cæli uno afpectu, manifeftum eft, quòd non poteft effe planæ figuræ, nec alicujus nifi sphærice, quoniam fuper Sphæram parvam poffunt cadere perpendiculares infinita, quæ à magno corpore veniunt, & tendunt in centrum Sphæra: & fic magnum corpus poteft ab oculo parvo videri. For the Demonftration of which he hath given us a Figure. Rog. Bacon. Perfpe&t. Diftin&t. 4. cap. 4.

Dr. Briggs faith, Pars antica, (five Cornea,) convexior eft poflica: hac enim ratione radii meliùs in pupillam detorquentur, & Oculi fundus ex altera parte in majorem (propter imagines rerum ibidem delineandos) expanditur. Ibid. Sect. 2.

(c) Suppofe the Eye had the Retina, or back Part, flat for the Reception of the Images, as in Fig. 1. AB A; it is manifeft, that if the Extremes of the Image A A were at a due focal Distance, the Middle B would be too nigh the Crystalline, and confequently appear confufed and dim; but all Parts of the Retina lying at a due focal Distance from the Crystalline, as at ACA, therefore the Image painted thereon is feen diftinct and clear. Thus in a dark Room, with a Lens at a Hole in the Window, (which Sturmius calls his Artificial Eye, in his Exercitat. Acad. one of which he had made for his Pupils, to run any where on Wheels): In this Room, I fay, if the Paper that receives the Images be too nigh, or too far off the Lens, the Image will be confufed and dim; but in the Focus of the Glafs, diftinct, clear, and a pleasant Sight,

A

Part

Part of that little darken'd Cell, is neatly adapted regularly to receive the Images from without, and to convey them accordingly to the common Sensory in the Brain.

To this we may add the Aptitude of this Figure to the Motion of the Eye, for it is neceffary for the Eye to move this way, and that way, in order to adjust itself to the Objects it would view; fo by this Figure it is well prepared for fuch Motions, fo that it can with great Facility and Dexterity direct itfelf as Occafion requires.

And as the Figure, fo no lefs commodious is,

2. The Situation of the Eye; namely, in the Head (d), the most erect, eminent Part of the Body, near the moft fenfible, vital Part, the Brain. By its Eminence in the Body, it is prepared to take in the more (e) Objects. And by its Situation in the Head, befides its Proximity to the Brain, it is in the most convenient Place for Defence and Security. In the Hands, it might indeed (in Man) be rendered more eminent than the Head, and be turned about here and there at Pleafure: But then it would be exposed to many Injuries in that active Part, and the Hands (f) rendered a lefs active and ufeful Part. And the like may be faid to its Sight, in any other Part of the Body, but where it is. But in the Head, both of Man, and other Animals, it is placed in a Part that feems to be contriv

(d) Blemmyis traduntur capita abeffe, Ore & Oculis pectore affixis. Plin. Nat. Hift. lib. v. cap. 8. Occidentem verfùs quofdam fine cervice Oculos in humeris habentes. Ibid. lib. vii. cap. 2. From thefe, and other fuch like Fables, in this laft cited Chapter of Pliny, no doubt our famous Romancer, Sir J. Mandevile, had his Romantick Stories related in his Travels. (e) See Book V. Chap. ii. Note (e).

(f) Galen deferves to be here confulted, who, in his Book De Ufu Partium, from many Confiderations of the Hand, fuch as what is here mentioned, as alfo its Structure, Site, and Use, largely proves and reflects upon the Wisdom and Providence · of the Contriver and Maker of that Part.

ed

ed and made, chiefly for the Action of the principal Senfes.

Another Thing obfervable in the Sight of the Eye, is the Manner of its Situation in the Head, in the Fore part, or Side-part thereof, according to the particular Occafions of particular Animals. In Man, and fome other Creatures, it is placed to look directly forward chiefly; but withal it is fo ordered, as to take in near the Hemisphere before it. In Birds, and fome other Creatures, the Eyes are fo feated, as to take in near a whole Sphere, that they may the better seek their Food, and escape Dangers. And in fome Creatures they are feated fo as to fee best behind them (g), or on each Side, whereby they are enabled to fee their Enemy that purfues them that Way, and fo make their Escape.

And for the Affiftance of the Eyes, and fome of the other Senfes in their Actions, the Head is generally made to turn here and there, and move as Occafion requires. Which leads me to the

3. Thing to be remarked upon, the Motions of the Eye itself. And this is generally upwards, downwards, backwards, forwards, and every Way (h), for the better, more easy, and diftinct Reception of the vifual Rays.

But where Nature any way deviateth from this Method, either by denying Motion to the Eyes, or the Head (i), it is a very wonderful Provifion fhe hath

(g) Thus in Hares and Conies, their Eyes are very protuberant, and placed fo much towards the Sides of their Head, that their two Eyes take in nearly a whole Sphere: Whereas in Dogs (that pursue them) the Eyes are fet more forward in the Head, to look that Way more than backward.

(b) Sed lubricos Oculos fecit [Natura] & mobiles, ut & declinarent fiquid noceret; & afpectum, quo vellent, facilè converterent. Cicer. de Nat. Deor. lib. ii. cap. 57. ·

(i) The Eyes of Spiders, (in fome four, in fome fix, and in fome eight) are placed all in the Fore-front of their Head (which

is

hath made in the Cafe. Thus for a Remedy of this Inconvenience, in fome Creatures their Eyes are fet out at a Diftance (k) from the Head, to be circumvolved here and there; or, one this, the other that Way, at Pleasure. And in Creatures, whose Eyes are without Motion, as in divers Infects; in this Cafe, either they have more than two Eyes, or their Eyes are nearly two protuberant Hemifpheres, and each Hemifphere often confifting of a prodigious Number of other little Segments of a Sphere (1). By which Means thofe Creatures are fo far from be

is round, and without any Neck), all diaphanous and transparent, like a Locket of Diamonds, &c. Neither wonder why Providence fhould be fo anomalous in this Animal, more than in any other ve know of. For, 1. Since they, wanting a Neck, cannot move their Head, it is requifite that Defect should be fupplied by the Multipli city of Eyes. 2. Since they were to live by catching fo nimble a Prey as a Fly is, they ought to fee her every W Vay, and to take her per faltum (as they do), without any Motion of the Head to difcover her: Which Motion would have feared away fo timorous an Infect. Power's Microf. Obferv. p. 11.

The Eyes of the Cameleon refemble a Lens, or Convex-Glass, fet in a verfatile globular Socket, which he turneth backward, or any Way, without moving her Head; and ordinarily the one a contrary or quite different Way from the other. Dr. Goddard in Phil. Trani. N° 137.

But what is more extraordinary in this Motion [of the Came leon's Eye] is to fee one of the Eyes move, whilft the other remains immoveable; and the one to turn forward, at the fame Time that the other looketh behind; the one to look up to the Sky, when the other is fixed on the Ground. And thefe Motions to be so extreme, that they do carry the Pupilla under the Creft which makes the Eye-brow, and Jo far into the Canthi, or Corners of the Eyes, that the Sight can discern whatever is done juft behind it, and directly before, without turning the Head, which is fastened to the Shoulders. Mem. for an Hift, in Anatom. Diffect. at Paris, Diff. of Camel. p. 22.

(k) Snails fend out their Eyes at a Distance, they being contained in their four Horns, like atramentous Spots, fitted to the End of their Horns, or rather to the Ends of thofe black Filaments or Optick Nerves, which are fheathed in her Horns, as Dr. Power wordeth it. Obferv. 31. p. 36. So the ingenious Dr. Lifter, Exercit. Anat. Cochl. Limac.

(1) See Book VIII. Chap. iii. Note (a).