QA PHILOSOPHICAL TRANSACTIONS. [aNNO 1684. 



mentioned ; as if through a microscope, I had beheld a piece of a scale of the 

 crystalline body of the eye. Or closing one eye, I hold the fingers of my hand 

 before the other eye, so close together, that they leave but a small opening 

 between them : this small space between the fingers, through which the eye 

 receives the light of the candle, will represent a similar thread-like appearance, 

 as in the former instance. 



I have often been aware of a moisture lying on the outside of the pupil of 

 the eye, containing some very few small globules ; which, as often as we close 

 our eye-lids, change place. From hence may be learnt the necessity of the 

 eye-lids in us ; and why fishes, which continually live under water, need them 

 not. But should men and other animals, that live out of the water, not have 

 them, they would soon be blind : for if the e3'e-lids by their closing did not 

 constantly moisten the eye, its superficies would dry up and rumple; and espe- 

 cially in the sun, or before a hot fire. Also it is not improbable, that from the 

 inner part of the eye a moisture continually issues through the cornea tunica, 

 which by the eye-lids is cleansed off; for when I had examined several hogs eyes, 

 which had been scalded with hot water, to get off the hair, I mostly observed, 

 that a thin film, which was on the cornea tunica of the eye, was somewhat 

 singed; whereby it was easily separated from that film, which was immediately 

 under it ; and when I then pressed the eye a little between my fingers, I per- 

 ceived in several places, a thin watery matter to soak through the horny film, 

 and lie like a watery damp on a glass ; and when I continued this pressing for 

 some time, this watery damp increased into small drops, and at length run like 

 water in a stream. This ought not to seem strange, considering the parts of 

 the horny coat to be made of hollow vessels, like veins ; very thin, and spread 

 about in branches. 



I have lately taken the homy coat of an ox's eye, and have separated from 

 it 7 films, extremely thin ; in each of which, were a number of interwoven, 

 very clear, and transparent streaks; which I judge to be, many of them, blood 

 vessels; but so small, that they contain none of the globules which cause the 

 redness in the blood. By the rubbing of our eyes with the hand, we may so 

 press these blood vessels, until they become so stretched out, that some of 

 these bloody globules may get in, and remain there for some time, which may 

 cause that redness in our eyes which comes by thus rubbing them. 



But to return again to the eye-lids. As our muscles and other parts of our 

 bodies rest not, unless posited as they lie, when we were yet in the womb; in 

 like manner, the eye-lids are not at rest, till the eyes are closed ; and therefore 

 we cannot long continue the eye-lids open, but with force ; and, that the same 

 might not be wearied, we often close them, although we mind it not. I have 



