On semi-decussation of the optic nerves / by William Hyde Wollaston.

  • William Hyde Wollaston
Date:
1824
Catalogue details

Licence: Public Domain Mark

Credit: On semi-decussation of the optic nerves / by William Hyde Wollaston. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    28/60
    balance of two circumstances combined in the same repre- sentation, namely, ist. The general position of the face presented to the spectator ; and, sdly. The turn of the eyes from that position. With this previous knowledge of the influence which the general perspective of the face in a portrait, has upon the apparent direction of the eyes, we shall be prepared to exa- mine why, if they look at the spectator when he stands in front of the picture, they follow, and appear to look at him, in every other direction. If we consider the effect produced by our change of posi- tion with reference to any other perspective drawing, we find a similar permanence of apparent position of the objects represented with respect to ourselves, and corresponding change of direction with reference to the plane of represen- tation, or to the room in which it hangs ; and we shall be able, in this case, distinctly to trace its origin in the simplest principles of perspective drawing. When two objects are seen on the ground at different dis- tances from us in the same direction, one will appear and must be represented exactly above the other. The line join- ing them is an upright line on the plane of the picture, and represents a vertical plane passing through the eye and these objects. When objects that are at different elevations are said to be in a line with us, the strict meaning is, that they are so placed that a vertical plane from the eye would pass
    digitised image 1
    digitised image 2
    digitised image 3