A critical inquiry respecting a new membrane in the eye : discovered by Mr. George Hunsley Fielding, and described by him in a lecture delivered at Oxford, before the late meeting of the British Association for the Advancement of Science / by William Gordon.
- Gordon, William, 1800-1849.
- Date:
- 1832
Licence: Public Domain Mark
Credit: A critical inquiry respecting a new membrane in the eye : discovered by Mr. George Hunsley Fielding, and described by him in a lecture delivered at Oxford, before the late meeting of the British Association for the Advancement of Science / by William Gordon. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![tion.* In other words, Mr. Fielding infers tliat the image which is portrayed npon the Retina, by the luminous rays Avhich flow directly into the eye, is too faint for distinct vision, whilst that which is reflected upon it by the Membrana Versicolor is sufficiently vivid for the purpose. How far this idea is correct will shortly be seen. The Membrana Versicolor is separated from the Retina by the Tunica Jacobi: the light, there- fore, in passing to and from tlie Membrana Ver- sicolor will pass once through the Retina, and twice through the Tunica Jacobi. Now, we have shew n that all transparent bodies absorb a part of the luminous moleculse which enter them. The light, therefore, in passing through the Retina, will lose some of its rays ; as it passes through the Tunica Jacobi, another por- tion of it will be stifled ; on striking the Mem- brana Versicolor, a third, and (for reasons to be afterwards explained) a very considerable por- tion will be absorbed: what remains will be reflected. In its second passage through the Tunica Jacobi, more of its rays will be lost in the substance of this membrane ; so that, of the light which first entered the eye, a very diminished proportion m 'iW ultimately reach the Retina.— It a])pe.ars, tlierefore, that an image on the Retina, * Via. Mv. r.'s i-cct. T' '-i^-](https://iiif.wellcomecollection.org/image/b22285933_0036.jp2/full/800%2C/0/default.jpg)
