useful Part. And the like may be faid to its Site 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 contrived and made chiefly for the Action of the principal Senfes.

Another thing obfervable in the Site 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 feek their Food, and efcape Dangers. And in fome Creatures they are feated, fo as to fee beft behind them (7), or on each fide, 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 Senses 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 it self. And this is generally upwards downwards, backwards, forwards, and every way (8), for the better, more eafy, and diftinct Recepception of the visual Rays.

(7) Thus in Hares, and Conies, their Eyes are very protuberant, and placed fo much towards the fides of their Head, that their two Eyes take in nearly a whole Sphere: whereas in Dogs, (that purfue them,) the Eyes are far more forward in the Head, to look that way, more than backward.

(8) Sed lubricos Oculos fecit [Natura] & mobiles, ut & declina rent fiquid noceret; & afpectum, quo vellent, facile converterent. Cicer. de Nat. Deor. L. 2. c. 57.

(

But

But where Nature any way deviateth from this Method, either by denying Motion to the Eyes, or the Head (9), it is a very wonderful Provifion fhe hath made in the cafe. Thus for a Remedy of this Inconvenience, in fome Creatures their Eyes are fet out at a Distance (10) from the Head, to be circumvolved here and there, or one this, the other

(9) 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 round, and without any Neck) all diaphanous and transparent, like a Locket of Diamonds, &c. neither wonder why Providence should be so anomalous in this Animal, more than in any other we know of. For, I. Since they wanting a Neck, cannot move their Head, it is requisite that defed fhould be fupplied by the multiplicity of Eyes. 2. Since they were to live by catching fo nimble a Prey as a Fly is, they ought to fee her every way, and to take her per faltum (as they do) without any Motion of the Head to discover her: which Motion would havę feared away fo timorous an Infect. Power's Microf. Obfery. pag.

The Eyes of the Cameleon refemble a Lens, or Convex Glass, set in a versatile globular Socket, which she 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. Tran. Nr. 137.

But what is more extraordinary in this Motion [of the Cameleon's Eye] is to fee one of the Eyes move, whilst 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 fo extream, that they do carry the Pupilla under the Creft which makes the Eye-brow, and fo far into the Canthi, or Corners of the Eyes, that the Sight can difcern whatever is done justly behind it, and directly before, without turning the Head which is faftened to the Shoulders. Mem. for a Nat. Hift. in Anatom. diffect. at Parif. Diff. of Camel. pag.

(10) Snails fend out their Eyes at a diftance, they being contained in their four Horns; like atramentous Spots, fitted to the end of their Horns; or rather to the ends of those black Filaments or optick Nerves, which are fheathed in her Horns, as Dr. Power wordeth it. Obf. 31. pag. 36. So the ingenious Dr, Lifter. Exercit, Anat. Cochl. Bị Limas.

that

that way, at pleasure. And in Creatures, whofe 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 Hemisphere often confifting of a prodigious Number of other little Segments of a Sphere (11.) By which means thofe Creatures are fo far from being denied any Benefit, of that noble and most neceffary Sense, of Sight, that they have probably more of it than other Creatures, anfwerable to the Rapidity of their Flight, and brisk Motion; and to their Inquefts after Food, Habitation, or Repofitories of Generation, or fuch other Neceflity of the Animal.

4. Another admirable Provision in the Eye is, its Size; in fome Animals large, in fome little. It would be endless here to enumerate Particulars; as thofe of Quadrupeds, Birds, Infects, and other Terreftrial Animals. And as for Fifhes, they will fall under another part of my Survey.

I fhall, therefore, only take notice of its Size in one Creature, the Mole (12). As the Habitation of that uncouth Animal is wholly Subterraneous, its

(11) Vid. l. 8. c. 3. Note 1.

(12) Severinus is of Ariftotle's, Pliny's, and Alb. Magnus's Opinion, that the Mole hath no Sight; G. Seger denies any Humour to be therein, but thinks they may probably fee, because Nature made nothing in vain. But Borrichius faith, their Eyes have appendiculam nerveam in cerebrum euntem, cujus beneficio globuli illi [the little Eyes] extra pellem facilè poterant exferi, retrahique pro arbitrio In illis oculorum globulis humor aqueus copiofè fatis natabat ; cæterorum non nifi tenue veftigium. Blaf. Anat. Anim. c. 35.

Et quoniam Natura hoc vita genus ipfi deftinavit, etiam perquam exiguos Oculos-dedit eo concilio, ut ii, pretiofiffima corporis pars, d terra pulvere ne affligerentur. Ii infuper pilis tedi, &c. Humores illis oculis infunt, & tunica nigra, uvea, se prodit. Ad hos tramite alio nervus venit. Schneider in Blaf. ibid.

Lodging,

ifo

Lodging, its Food, its Exercises, nay, even all its Paftimes and Pleafures, are in thofe Subterraneous Receffes and Paffages, which its own Industry hath made for it felf; fo it is an admirable Provifion made in the Size of the Eye of that little Creature, to answer all its Occafions, and at the fame time to prevent Inconveniencies. For as a little Light will fuffice an Animal living always under Ground; fo the fmalleft Eye will abundantly fupply that Occafion. And as a large protuberant Eye, like that of other Animals, would much annoy this Creature in its principal Bufinefs, of digging for its Food and Paffage; fo it is endowed with a very small one, commodiously feated in the Head, and well fenced and guarded againft the Annoyances of the Earth.

5. Another thing remarkable in this noble part of Animals is, its Numbers; no lefs than two (13)

Some time fince I made divers accurate Diffections of the Eyes of Moles, with the help of Microscopes, having a doubt whether what we take to be Eyes, were fuch or no. But upon a ffric Scrutiny I plainly could diftinguish the Vitreous, and Chryftalline Humours, yea, the Ligimentum Ciliare, and the atramentaceous Mucus. The Pupil I could manifeftly difcern to be round, and the Cornea copped, or conical: The Eye is at a great diftance from the Brain, the Optick Nerve very flender, and long, reaching from the Eye through the intermediate Flefh, and fo paffeth to the Brain, along with the pair of Nerves reaching to the Nofe, which are much the largest that are in all the Animal. Thefs Creatures, I imagine, have the faculty of withdrawing their Eyes, if not quite into the Head, (as Snails) yet more or less within the Hair, as they have more or lefs occafion to ufe, or guard their Eyes.

Galen faith, Moles have Eyes, the Chryftalline and Vitreous Humours, encompaffed with Tunicks. De US. Part. I. 14. . 6. 6. So accurate an Anatomift was he for his Time.

(13) Pliny tells us of a fort of Heron with but one Eye, but 'twas only by hear-fay. Inter Aves Ardeolarum genere, quos Leucos vocant, altero oculo carere tradunt. Nat. Hift. 1. 11. c. 37. So the King of

the

in any Inftance, that I know of; and in fome Animals more, as I have already hinted (14).

Now this is an admirable Provision; firft, for the Convenience of taking in the larger Angle or Space And in the next place, the Animal is by this Provifion, in fome meafure, prepared for the Misfortune of the lofs of one of these noble, and neceffary Organs of its Body.

But then befides all this, there is another thing confiderable in this multiplicate Number of the Eye; and that is, that the Object seen is not multiplied as well as the Organ, but appears but one, though feen with two or more Eyes (15). A manifeft Sign of the infinite Skill of the Contriver of this fo noble a Part, and of the exquifite Art he employed

the Nigre that hath but one Eye, and that in his Forehead, 1..6. c. 30. Which Fables I take notice of more for the Reader's Di verfion, than any Truth in them.

(14) Supra, Note 9.

they

(15) The most celebrated Anatomists differ greatly about the reason why we fee not double with two Eyes. This Galen, and others after him, generally thought to be from a Collation or Decuffation of the Optick Nerves, behind the Of. Sphenoides. But whether they decuffate, coalefce, or only touch one another, do not well agree. The Bartholines exprefly affert they are united, non per fimplicem contactum vel interfectionem in bomine, fed tátalem fubftantia confufionem, Anat. 1. 3. c. 2. And whereas Kefa lius, and fome others had found fome Inftances of their being difunited they fay, fed in plerifque ordinariè confunditur interior fubftantia, ut accurata difquifitione deprehendi.

But our Learned Dr. Gibson, (Anat. 1.3.10.) faith, they are united by the clofeft Conjunction, but not Confufion of their Fibres ..But others think the reafon is not from any Coalefcence, Gontact, or croffing of the Optick Nerves, but from a Sympathy be tween them. Thus Monfieur Cartes is of Opinion, that the Fibrille conftituting the medullary Part of thofe Nerves being spread in the Retina of each Eye, have each of them correfponding Parts in the Brain; fo that when any of those Fibrille are ftruck by any part of an Image, the correfponding Parts of the Brain are there.

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