On the invention of stereoscopic glasses for single pictures : with preliminary observations on the stereoscope, and on the physiology of stereoscopic vision / by T. Wharton Jones.

  • Jones, Thomas Wharton, 1808-1891.
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: On the invention of stereoscopic glasses for single pictures : with preliminary observations on the stereoscope, and on the physiology of stereoscopic vision / by T. Wharton Jones. 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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    or the two figures of a stereoscopic slide, are seen as one, though that one is like neither of the per- spective images. In this case there must be a mental combination of the two into one. A superposition of two images does, indeed, appear to take place, if they are quite different from each other, either in respect to colour or shape. Thus, when impressions different in colour, though of the same shape, are made on corresponding parts of the two retinae,—which may be done by means of a Stereo- scope and a blank slide on which a blue wafer has been stuck on the one division, and a yeUow wafer on the other,—the images of the two wafers run together, and one round spot is seen, but an admix- ture of the two colours does not take place. The spot appears either blue alone or yeUow alone, at the same instant of time, as if the image of the one wafer was merely superposed over that of the other. Some- times, however, the blue is seen in part, and the yellow in part, as if portions of the superposed wafer had vanished, allowing of portions of the subjacent one to be seen through. If the colour of the one wafer be much more brilliant than that of the other, so that the impression on the one retina is more striking than that on the other, the more brilliant colour prevails or excludes the other altogether from the mind’s perception. When the impressions are entirely different in shape, though of the same colour, the images are perceived to alternate in a similar manner, unless the one be much more striking than the other, in which case it also, like the brightest colour, predominates, and the other is not perceived. As the dissimilar perspectives of an object of three dimensions or the two figures of a stereoscopic slide cannot aU fall on exclusively corresponding points of the two retinae, it follows that it is not an indispen- sable condition for single vision that every part of the impression on the two retinae be made on exactly