Observations on the nature and theory of vision : with an inquiry into the cause of the single appearance of objects seen by both eyes / by John Crisp, F.R.S.
- Crisp, John
- Date:
- MDCCXCVI [1796]
Licence: Public Domain Mark
Credit: Observations on the nature and theory of vision : with an inquiry into the cause of the single appearance of objects seen by both eyes / by John Crisp, F.R.S. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
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![[ 3 ] ¥/eils; in v/hich, I apprehend, Dr. Reid or Dr. Smith would concur. Whether this point C be or not the precife geome- trical centre of the retina, or whether the line C P does or does not pafs with jftridl accuracy through the centre of the eye, are circumftances which will not afFed:, the queftion we are confidering. Let O be fome luminous point in the optic axis or line C P, from which a pencil of rays is fuppofed to iffue covering the pupil ED, and which we know will be coUefted on the fame point C *. Now, what Dr. Smith and Dr. Reid have faid re- fpedling vifible diredlion is this : that the point O will not appear either in the direc- tion of the ray C E or of the ray CD, or of any intermediate ray between thefe and the ray CO; but that it will appear in the * The point O is fuppofed to be at fome diflance from the eye; if it were near, the point C would lie beyond the retina, but ftill in the optic axis produced. direction](https://iiif.wellcomecollection.org/image/b21175408_0134.jp2/full/800%2C/0/default.jpg)
