Objects are far off or near, because these Things are what are ufually taken notice of; but that which I fhall obferve is, the prodigious Art and Finery of its conftituent Parts, it being, according to fome late nice Microscopical Obfervations (ee), compofed

Befides all which Obfervables in the Choroeides, and inner Eye, I have alfo found this farther remarkable in the Scleroti ça, and outer-part of the Eye of Birds, viz. That the forepart of the Sclerotica is horny and hard, the middle-part thin and flexible, and Braces intervene between the fore and hindpart, running between the Choroeides and Sclerotica; by which Means the Cornea, and back-part of the Eye, are brought to the fame Conformity, that the reft of the Eye hath.

The great End and Defign of this fingular and curious Apparatus in the Eyes, both of Birds and Fishes, I take to be, 1. To enable thofe Creatures to fee at all Distances, far off, or nigh; which (especially in the Waters) requireth a different Conformation of the Eye. In Birds alfo, this is of great Ufe, to enable them to fee their Food at their Bill's End, or to reach the utmost Distances their high Flights enable them to view; as to fee over great Tracts of Sea or Land, whither they have occafion to fly; or to fee their Food or Prey, even finall Fiches in the Waters, and Birds, Worms, &c. on the Earth, when they fit upon Trees, high Rocks, or are hovering high in the Air. 2. To enable thofe Animals to adapt their Eye to all the various Refractions of their Medium. Even the Air it felf varies the Refractions, according as it is rarer or denfer, more or less compreffed; as is manifest from the learned and ingenious Mr. Lowthorp's Experiment in Phil. Tranf. No. 257. and fome other Experiments fince of the before-commended Mr. Hawksbee, both in natural, rarify'd and compreffed Air; in each of which, the Refractions conftantly varied in exact Proportion to the Rarity or Denfity of the Air. Vid. Hawkfbee's Exp. pag. 175,

c.

Befides this Conformity in general, between the Eyes of Birds and Fishes, Du Hamel tells us of a fingular Confor mity in the Cormorant's Eye, and that is, that the Crystalline is globous, as in Fifhes, to enable it to fee and pursue its Prey under Water: Which J. Faber, in Mr. Willoughby faith, they do with wonderful Swiftness, and for a long Time. Will. Ornithol. p. 329.

(ee) The Crystalline Humour, when dry'd, doth manifeftly enough appear to be made up of many very thin fpherical

Lamina,

105 posed of divers thin Scales, and thefe made up of one fingle minutest Thread or Fibre, wound round and round, fo as not to cross one another in any one Place, and yet to meet, fome in two, and fome in more different Centers; a Web not to be woven, an Optick Lens, not to be wrought by any Art lefs than infinite Wisdom.

Laftly, To conclude the Parts of this admirable Organ, I fhall make only one Remark more, and that is about its Nerves. And here, among others, the admirable Make of the Optick Nerves might deserve to be taken notice of in the first Place, their Medullary Part (ff) terminating in the Brain it felf, the Teguments propagated from the Meninges, and terminating in the Coats of the Eye, and their commodious Infertions into the Ball of the Eye, in fome directly oppofite to the Pupil of the Eye, in others

Mr. Lewenhoek

Lamine, or Scales lying one upon another. reckons there may be 2000 of them in one Crystalline, from the outermoft to the Center. Every one of thefe Scales, he faith, he hath difcovered to be made up of one fingle Fibre, or finest Thread wound, in a moft ftupendous Manner, this way, and that way, fo as to run feveral Courses, and meet in as many Centers, and yet not to interfere, or cross one another, in any one Place. In Oxen, Sheep, Hogs, Dogs and Cats, the Thread fpreads into three feveral Courses, and makes as many Centers: In Whales five; but in Hares and Rabbets only two. In the whole Surface of an Ox's Cryftalline, he rec kons there are more than 12000 Fibres juxtapofited. For the right and clear Understanding of the Manner of which admirable Piece of Mechanifm, I fhall refer to his Cuts and Defcriptions in Philof. Tranf. No. 165. and 293. The Truth hereof I have heard fome ingenious Men queftion; but it is what I my felf have feen, and can fhew to any Body, with the Help of a good Microscope.

(ff) S. Malpighi obferved the Middle of the optick Nerve of the Sword-Fish, to be nothing elfe but a large Membrane, folded according to its Length in many Doubles, almoft like a Fan, and invefted by the Dura mater; whereas in LandAnimals it is a Bundle of Fibres. V. Phil. Tranf. No. 27.

obliquely

obliquely towards one Side (gg). But most of these Things have been treated of, and the Convenience hereof fet forth by others that have written of God's Works. I fhall therefore take notice only of one wife Provifion the Creator hath made about the Motion of the Eye, by uniting into one the Third Pair of Nerves, called the Motory Nerves (bb), each of which fending its Branches into each Mufcle of each Eye, would cause a Distortion in the Eyes; but being united into one, near their Infertion into the Brain, do thereby cause both Eyes to have the fame Motion; fo that when one Eye is moved this way and that way, to this and that Object, the other Eye is turned the fame way also.

Thus from this tranfient and flight View (I may call it) of the Parts of the Eye, it appears what an admirable Artift was the Contriver thereof. And now in the

Seventh and laft Place, Let us confider what Provifion this admirable Artift hath made for the Guard and Security of this fo well formed Organ (ii). And

here

(g) Certiffimum eft, quòd in omnibus Oculis humanis (quos faltem mihi diffecare contigit) Nervus opticus Pupilla è diametro epponitur, &c. Briggs's Ophthal. c. 3. §. 15. Ita Willis de 4nim. Brut. p. 1. c. 15.

Nervi Optici in nobis, item in Cane, Fele ( in cateris forfan animalibus calidis) ad fundum Oculi delati Pupilla regioni profpiciunt, dum interim in aliis Quadrupedibus, uti etiam in Pifcibus & Volueribus, obliquè femper Tunica Sclerotidi inferuntur. Unde, &c. Willis 1b. c. 7. §. 11.

(bb) This Pair is united at its Rife; whence is commonly drawn a Reason why one Eye being mov'd towards an Object, the other is directed alfo to the fame. Gibfon's Anat. Book III. Chap. 11. So Bartholine Anat. Libellus 3. c. 2.

(ii) Among all the other Security the Eye hath, we may reckon the Reparation of the aqueous Humour; by which Means the Eye when wounded, and that in all Appearance very dangerously too, doth often recover its Sight: Of which Bera. Verzascha gives divers Examples ancient and modern, One is from Galen, of a Boy fo wounded, that the Cornea

fell,

here we shall find the Guard equivalent to the Ufe and Excellency of the Part. The whole Organ fortified and fenced with ftrong, compact Bones, lodged in a strong, well made Socket, and the Eye it felf guarded with a nice made Cover (kk). Its Humours, and its inward Tunicks, are indeed tender, propor

fell, and became flaccid, but yet recovered his Sight. Other fuch like Inftances alfo he gives from Realdus Columbus, Rhodius, and Tulpius; and one that he cured himself in thefe Words, Ego in Nobiliffimi viri filiolâ fimilem cafum obfervavi: hac dum levibus de caufis cum fratre altercaret, ifte iracundiâ percitus cultellum Scriptorium apprehen.lit, & fororis oculo vulnus infligit, inde humor aqueus effluxit. Vocatus prafentem Chirurgum juffi fequens collyrium anodynum & exficcans tepide fapiùs admovere. R aq. Plantag. Ziv. Rofar. Sanicul, Euphraf ana Trochifc. alb. Rhaf. cum Opio ii. Tutia pp. 9, Croci orient. 9. M. Hoc Collyrium inflammationem compefcuit, vulnus ficcavit fanavit. Hinc poft aliquot menfes Humor aqueus fuccrevit. Nam vifus, fed dibilior, cum fummo parentum gaudio redivit. B. Verzafchæ Obferv. Medicæ. Obf. 14.

Another Cure of this kind, was experimented by Dr. Da niel Major, upon a Goofe, Ann. 1670. the aqueous Humour of both whofe Eyes they let out, fo that the Eyes fell, and the Goofe became quite blind: But without the Ufe of any Medicine, in about two Days Time, Nature repaired the watery Humour again, the Eyes returned to their former Turgency, and the Goofe was in a Week after produced seeing before twenty eight or thirty Spectators. Ephem. Germ. T. 1. Add. ad. Obf. 117.

From the fame Caufe, I doubt not, it was that the Eye of a Gentleman's Daughter, and thofe of a Cock, when wounded, fo that the Cornea funk, were reftored by a Lithuanian Chymift, that paffed for a Conjurer, by the Ufe of a Liquor found in May, in the Veficulæ of Elm. Of which fee Mr. Ray's Catal. Cantab. in Ulmus from Henr. ab Heers.

(kk) Palpebra, qua funt tegumenta Oculorum, molliffima tatu, ne laderent aciem, aptiffime facte, e ad claudendas Pupillas, nè quid incideret, & ad aperiendas; idque providit, ut identidem fieri poffet cum maximâ celeritate. Munitaque funt Palpebra tanquàm vallo pilorum: quibus & apertis Óculis, fi quid incideret, repelleretur, & fomno conniventibus, cùm Oculis ad cernendum non egerimus, ut qui, tanquàm involuti, quiefcerent. Latent pratereà utiliter, & excelfis undique partibus

Sepiuntur.

Book IV. proportionate to their tender, curious Ufes; but the Coats without, are context and callous, firm and strong. And in fome Animals, particularly Birds

fepiuntur. Primism enim fuperiora Superciliis obducta fudorem à capite, & fronte defluentem repellunt. Gena deinde ab inferiore parte tutantur fubjecta, leviterque eminentes, Cicer. de Nat. Deor. L. 2. c. 57.

Tully, in the Perfon of a Stoick, having fo well accounted for the Ufe of the Eye Lids, I fhall for a further Manifeftation of the Creator's Contrivance and Structure of them, take notice of two or three Things: 1. They confift of a thin and flexible, but ftrong Skin, by which means they the better wipe, clean, and guard the Cornea. 2. Their Edges are fortified with a foft Cartilage, by which means they are not only enabled the better to do their Office, but also to clofe and fhut the better. 3. Out of thefe Cartilages grow a Pallifade of ftiff Hairs, of great Ufe to warn the Eye of the Invafion of Dangers, to keep off Motes, and to shut out too exceffive Light, ec. and at the fame time to admit of (through their Intervals) a fufficient Paffage for Objects to approach the Eye. And it is remarkable, that thefe Hairs grow but to a certain, commodious Length, and need no cutting, as many other Hairs of the Body do: Alfo, that their Points ftand out of the way, and in the upper-lid bend upwards, as they do downwards in the lower lid, whereby they are well adapted to their Ufe. From which laft Obfervables, we may learn how critical and nice the great Author of Nature hath been, in even the leaft and most trivial Conveniencies belonging to Animal Bodies; for which Reafon I have added it to Tully's Remarks. And more might have been added too, as particularly concerning the curious Structure and Lodgment of the Right Muscle, which opens the Eye-Lids; and the Orbicularis, or Circular one, that fhuts them; the nice Apparatus of Glands that keep the Eye moift, and ferve for Tears; together with the Reason why Man alone, who is a facial Animal, doth exhibit his focial Affections by fuch outward Tokens as Tears; the Nerves alfo, and other Organs acting in this Miniftry. I might alfo fpeak of the Paffages for difcharging the fuperfluous Moisture of the Eyes through the Noftrils, and much more of the like kind. But it would take up too much Room in these Notes; and therefore it fhall fuffice to give only fuch Hints as may create a Sufpicion of a noble OEconomy and Contrivance in this (I had almoft faid) leaft confiderable part of the Eye. But for

Particulars