Page:Philosophical Transactions - Volume 003.djvu/44

, that the Impediment of his Hearing was of the like nature with the other.

Aving often observed in Anatomical Dissections of Men as well as Brutes, that the Optick Nerve does never answer just to the Middle of the bottom of the Eye, i.e. to the place, where is made the picture of the Objects, we directly look on; and that in man it is somewhat higher, and on the side towards the Nose; to make therefore the Rayes of an Object to fall upon the Optick Nerve of my Eye, and to find the consequence thereof, I made this Experiment;

I fastn'd on an obscure Wall, about the hight of my Eye, a small round paper, to serve me for a fixt point of Vision; andl fastned such an other on the side thereof towards my right hand, at the distance of about 2. foot; but somewhat lower than the first, to the end that it might strike the Optick Nerve of my Right Eye, whilst I kept my Left shut. Then I plac'd my self over against the First paper, and drew back by little and little, keeping my Right Eye fixt and very steddy upon the same; and being about 10. foot distant, the second paper totally disappear'd.

That this cannot be imputed to the Oblique position of the second paper, is hence evident. That I can see other Objects further extant on the side of it, so that one would believe, the second paper were by a flight taken away, if one did not soon finde it again by the least flirting of one's Eye.

This Experiment I made often, varying it by different distances, and removing or approaching the Papers to one another proportionally, I made it also with my left Eye, by keeping my Right shut, after I had fastned the Second paper on the Left side of my point of Vision; so that from the Site of the parts of the Rh