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XLIII.—On the Knowledge of Distance given by Binocular Vision

Published online by Cambridge University Press:  17 January 2013

David Brewster
David Brewster
Affiliation:
St Leonard's College, St Andrews
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Extract

In analysing Mr Wheatstone's beautiful discovery, that in binocular vision we see all objects of three dimensions by means of two dissimilar pictures on the retina, I trust I have satisfied the Society that the dissimilarity of these two pictures is in no respect the cause of our vivid perception of such objects, but, on the contrary, an unavoidable accompaniment of binocular vision, which renders it less perfect than vision with one eye. On the other hand, it is quite true that, in Mr Wheatstone's experiment of producing the perception of objects of three dimensions by the apparent coalescence of two dissimilar representations of such objects in plano, the dissimilarity of the pictures is necessary in the exhibition of that beautiful phenomenon.

Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 15 , Issue 4 , 1844 , pp. 663 - 675
Copyright
Copyright © Royal Society of Edinburgh 1844

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References

page 667 note * This effect is finely seen in the diagram of the Homogeneous Curve, which forms Plate IX. of Mr Hay's work “On the Harmony of Form.”

page 670 note * Smith's Optics, vol. ii. p. 388, § 977.

page 670 note † Essay on Single Vision, &c., p. 44.

page 673 note * Malebranche seems to have been the first who introduced the apparent distance of objects as an element in our estimate of apparent magnitude. De la Recherche de la Verité, tom. i. liv. i.; tom, iii. p. 354. See also Bouguer, Mem. Acad. Par. 1755, p. 99. These views, however, have been abandoned by several subsequent writers, and the real distance of objects has been substituted for their apparent distance. Varignon, Mem. Acad. Par. 1717, p. 88. M. Lehot, for example, says, “L'expression de la grandeur visuelle d'un corps est egale à la grandeur reelle, multipliée par le logarithme de la distance reelle divisée par cette distance.” Nouvelle Théorie de la Vision, 1er Mem. Suppl. p. 7, 8. Paris, 1823. This estimate of distance is incompatible with experiment and observation.