Carpenter's principles of human physiology . a ground-glassplate at the image produced by the coalescence of the two images of a stereoscopic slide, eachrefracted by a separate lens.—See Proceed, of Royal Society, vol. ix. 1857-59, p. 194. + The most striking effect is produced by two photographic pictures, taken at the sametime by two cameras, so placed that their axes shall form the same angle with each other asthat which the axes of the two eyes would form when looking at the same object. This adapta-tion, though the credit has been assumed by others, was originally devised by Prof. Wheatst
Carpenter's principles of human physiology . a ground-glassplate at the image produced by the coalescence of the two images of a stereoscopic slide, eachrefracted by a separate lens.—See Proceed, of Royal Society, vol. ix. 1857-59, p. 194. + The most striking effect is produced by two photographic pictures, taken at the sametime by two cameras, so placed that their axes shall form the same angle with each other asthat which the axes of the two eyes would form when looking at the same object. This adapta-tion, though the credit has been assumed by others, was originally devised by Prof. Wheatstone. 742 OF THE ORGANS OF THE SENSES, AND THEIR FUNCTIONS. delineations of simple geometrical figures, easily suggested to the mind ; andit may be readily shown that the very same outlines will sxxggest differentconceptions, according to the mode in which they are placed. Thus in , the upper part of figures a, b, when combined in the Stereoscope, excitethe idea of a projecting-truncated pyramid, with the small square in the centre,. Fig. 272 and the four sides sloping equally away from it ; whilst the lower pair offigures, c, d, which are the same as the upper, but transferred to the oppositesides, no less vividly bring before the mind the visual conception of a recedingpyramid, still with the small square in the centre, and the four sides sloping equally towards it. —Prof. Wheatstone hasfurther shown, by meansof the Stereoscope, thatsimilar images, differingto a certain extent inmagnitude, when pre-sented to the correspond-ing parts of the tworetina?, give rise to theperception of a singleobject, intermediate insize between the twomonocular it not for this,objects would appearsingle only when at anc d equal distance from both eyes, so that their pictures upon the retina? are of the same size ; which will nothappen unless they are directly in front of the median line of the face. Again,if pictures of dissimilar objects be simultaneously presented to the
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