Volume 1

Paley's Natural theology / with illustrative notes, by Henry, Lord Brougham and Sir Charles Bell to which are added supplementary dissertations, by Sir Charles Bell.

  • Paley, William, 1743-1805.
Date:
1836
Catalogue details

Licence: Public Domain Mark

Credit: Paley's Natural theology / with illustrative notes, by Henry, Lord Brougham and Sir Charles Bell to which are added supplementary dissertations, by Sir Charles Bell. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    spaces C, C, are deprived of rays by the intervention of the iris A, A. Yet this in no measure affects the size of the image but only diminishes the intensity of its illumination. By the contraction of the iris, and consequent enlarge- ment of the pupil, a larger pencil of rays is admitted. It is remarkable that the image formed on the retina must always be inverted, and yet such is the power of habit and experience, derived from touching objects, that we see things as they are in reality, and not as they are painted in our eyes—experience thus correcting the errors of sense. It is in the same way that we see single, though we have an image made in each eye. But if we change the ordinary position of our eye, the habit is broken, and we see double.] I. In order to exclude excess of light, when it is excessive, and to render objects visible under obscurer degrees of it, when no more can be had, the hole or aperture in the eye, through which the light enters, is so formed as to contract or dilate itself for the purpose of admitting a greater or less number of rays at the same time. The chamber of the eye is a camera-obscura, which, when the light is too small, can enlarge its open-