Instinct and reason: deduced from electro-biology / By Alfred Smee.

  • Alfred Smee
Date:
1850
Catalogue details

Licence: Public Domain Mark

Credit: Instinct and reason: deduced from electro-biology / By Alfred Smee. Source: Wellcome Collection.

    56/376 page 20
    part at the back, when, on holding the eye towards the candle, a beautiful inverted image of the flame is depicted upon the part scraped. Fig. 3. Fig. 3.—Vertical section of the eye.—a a a, Sclerotic coat, or white of the eye. b b, Cornea, or glassy part through which we see. rrrr, Retina, or nervous expanse : the choroid lies between the retina and sclerotic, o, Optic Nerve. In the diagram it appears to be in the axis of the eye, but in reality it is about the of an inch from the axis on its inner side, and a little above the median line. In the axis is a spot called the foramen of Sommering, which is in fact the point of most distinct vision. e,f, Iris, or curtain, d, Anterior chamber, or aqueous humour, c, Lens. g g, Ciliary processes, for the adjustment of the eye to distance, v v, Vitreous humour. 46. A camera obscura Fig. 4. {Jig. 4), however, re¬ quires the lens to be ad¬ justed to suit different distances. In all instru¬ ments of this character a contrivance exists by which the lens can be moved backwards and forwards to suit different distances; otherwise, the image might be formed behind (5r before the medium placed to receive it, as in the subjoined wood-cuts {fig. 5,6). There is much difference of opinion as to how this
    digitised image 1
    digitised image 2
    digitised image 3