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för this Ufe, and which are otherwise in Birds, than in Man, where the Ductus paffes not beyond the Glandula lachrymalis. For in Birds it goes beyond; and penetrating above half way on the internal Eye-lid, it is opened underneath upon the Eye: Which is evidently done to spread a Liquor over the whole Cornea, when this Eye-lid paffes and repaffes; as we obferv'd it to do every moment.

The Artifice and Contrivance of Nature, for the extending and withdrawing of this Curtain of the Periophthalmium in Birds, is admirable, but it is difficult fo to exprefs it in Words, as to render it intelligible to the Reader; for a multitude of Words doth rather obscure than illuftrate, they being a Burden to the Memory, and the first apt to be forgotten, before we come to the laft. So that he that uses many Words for the explaining any Subject, doth, like the Cuttle-Fish, hide hinfelf, for the most part, in his own Ink. And in the Description of the Figure, and Manner of the Extenfion and Contraction of this Membrane, the Pari fian Academifts are conftrained to use so many Words, that I am afraid few Readers Patience and Attention will last so long, as to comprehend and carry it away: Yet because it is fo evident and irrefragable a Proof of Wisdom and Defign, I could not omit it. Their Words are thefe, The Particularities of the admirable Structure of this Eye-lid, are fuch things as do diftinctly discover the Wisdom of Nature, a mong a thousand others, of which we perceive Z

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Part II. not the Contrivance, because we understand: them only by the Effects, of which we know. not the Causes; but we here treat of a Machine, all the Parts whereof are visible, and which need only to be lookt upon, to discover the Reafon of its Motion and Action.

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This Internal Eye-lid in Birds is a Membranous Part, which is extended over the Cornea, when it is drawn upon it like a Curtain, by a little Cord or Tendon; and which is drawn back again into the great Corner of the Eye, to uncover the Cornea, by the Means of the very ftrong Ligaments that it has, and which, in drawing it back towards its Origine, do fold it up. It made a Triangle when extended, and it had the Figure of a Crefcent when folded: up. Its Bafis (which is its Origine) was toward the great Corner of the Eye, at the Edge of the great Circle, which the Sclerotica forms when it is flatted before, making an Angle with its anterior Part, that is the Cornea, which is raised like a Hill upon it. The Bafis, which is the Part immoveable, and faftned to the Edge of the Sclerotica, did take up more than a third Part of the Circumference of the great Circle of the Sclerotica; the fide of the Triangle, which is toward the little Corner of the Eye, and is moveable, was reinforced with a Border, which fupplies the place of the Tarfus, and which is black in most Quadrupeds. This fide of the Eye-lid, is that which is drawn back into the Corner of the Eye, by the Action of the Fi bres of the whole Eye-lid, which parting from

its Origine, proceed to join themfelves to its Tarfus.

To extend this Eye-Lid over the Cornea, there were two Muscles that were feen, when fix were taken away, which ferv'd to the Motion of the whole Eye. We found that the greatest of these two Muscles has its Origine at the very Edge of the great Circle of the Sclerotica, towards the great Corner, from whence the Eye-Lid takes its Original. It is very fleshy in its Beginning, which is a large Bafis from whence coming infenfibly to contract itfelf by paffing under the Globe of the Eye, like as the Eye-Lid paffes over it, it approaches the Optick Nerve, where it produces a Tendon round and flender, fo that it paffes through the Tendon of the other Mufcle, which ferves for a Pully, and which hinders it from preffing the Optick Nerve upon which it is bent, and makes an Angle, to pass through it to the upper Part of the Eye: And coming out from underneath the Eye to infert itself at the Corner of the Membrane, which makes the Internal Eye-Lid. This fecond Muscle hath its Original at the fame Circle of the Sclerotica, but oppofite to the firft, towards the little Corner of the Eye, and paffing under the Eye like the other, goes to meet it, and embraces its Tendon, as has been declared.

The Action of these two Muscles is, in respect to the firft, to draw by the means of its Cord or Tendon, the Corner of the Internal Eye-Lid, and to extend it over the Cornea. As

Part II. to the second Muscle, its Action is by making its Tendon to approach towards its Origine, to hinder the Cord of the first Muscle which it embraces, from hurting the Optick Nerve; but its principal Ufe is, to affift the Action of the first Muscle. And 'tis herein that the Mechanism is marvellous in this Structure, which makes that these two Muscles joined together, do draw much farther than if it had but one. For the Inflexion of the Cord of the first Mufcle, which causes it to make an Angle on the Optick Nerve, is made only for this End: And a fingle Muscle with a ftrait Tendon, had been fufficient, if it had Power to draw far enough. But the Traction which must make the EyeLid extend over the whole Cornea, being neceffarily great, it could not be done but by a very long Mufcle; and fuch a Muscle not being able to be lodg'd in the Eye all its Length, there was no better Way to fupply the Action of a long Muscle, than by that of two indifferent ones, and by bending one of them, to give it the greater Length in a little Space. Thus far the Academifts, who themselves reflecting on the Length and Obfcurity of this Defcription, tell us, that the Infpection of the Figure, will ferve greatly to the Understanding of it, which the Novelty of the Thing renders obfcure in itself; and fo I fear it will be to moft Readers; howbeit in fuch a Work as this, I ought not by any means, as I faid be fore, to leave out fuch a notable Instance,

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343 wherein Contrivance and Defign do fo clearly and undeniably appear.

The fame Academifts, as I remember, tell us, that they have found by Experience, that the aqueous Humour of the Eye will not freeze; which is very admirable, féeing it hath the Perfpicuity and Fluidity of common Water, and hath not been taken Notice of, fo far as I have heard, to have any eminent Quality difcoverable, either by Tafte or Smell fo that it must be of fome Singular and Ethereal Nature: And deferves to be examined and annalized by the curious Naturalists of our Times.

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The Providence of Nature is wonderful in a Camel, or Dromedary, both in the Structure of his Body, and in the Provision that is made for the Suftenance of it. Concerning the firft, I fhall inftance only in the Make of his Foot; the Sole whereof, as the Parifian Academifts do obferve, is flat and broad, being very fleshy, and covered only with a thick, soft, and somewhat callous Skin, but very fit and proper to travel in fandy Places, fuch as are the Defarts of Africk and Afia. We thought (fay they) that this Skin was like a living Sole, which wore not with the Swiftnefs and the Continuance of the March, for which this Animal is almost indefatigable. And it may be this Softnefs of the Foot, which yields and fits itself to the Ruggedness and Uneavenness of the Roads, does render the Feet lefs capable of being worn, than if they were more folid,

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