Investigations in the relation between convergence and accommodation of the eyes / by Ernest E. Maddox.

  • Maddox, Ernest E. (Ernest Edmund), 1860-1933.
Date:
[1886]
Catalogue details

Licence: Public Domain Mark

Credit: Investigations in the relation between convergence and accommodation of the eyes / by Ernest E. Maddox. Source: Wellcome Collection.

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

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    10, INVESTIGATIONS IN THE RELATION BETWEEN CON- VERGENCE AND ACCOMMODATION OF THE EYES. By Ernest E. Maddox, M.B. Edin., Syme Surgical Fdloio in the University of Edinburgh} Why, if we see separately with each eye, do we not see double when both are used? This problem has taxed the ingenuity of many busy minds in past ages, and its history is by no means one of uniform progress. Euclid, two or three centuries B.C., had advanced so far beyond some at a far later date as to recognise that both eyes were employed in unison, and that their dissimilar pictures were in some way united. Galen surmised that the union of the optic nerves at the commissure supplied a clue. Both he and Herophilus assumed that the two nerves were there united by mysterious pores; doubtless to permit the free passage and intercourse of the little spirits of both sides, whose remarkable unanimity in fitting the pictures together was evidenced by single vision. Later on Gassendus, Tacquet, and Joan Baptista Porta, the inventor of the camera obscura, escaped the difficulty altogether by assuming that one eye only at a time wa3 engaged in vision. In 1613, Francis Aguillon (Aguilonius), a learned Jesuit, called in the aid of what he termed a common sense, which imparts its aid equally to each eye, exerting its own power equally in the same manner as the eyes are converged by means of their optical axes. This was an advance, for the two pictures, we may truly say, are mentally united by a common sense,2 of the real nature of which we probably know little more than Aguilonius, though we may notice more of its effects. Dr Briggs appears to have been the first to have suggested cor- responding or identical points in the two retinpe, that is, that each point on the inner side of one retina has a corresponding point on the outer side of the other, so that when images are thrown by an object upon these identical points, they are mentally united. This was a great advance, though the theory of identical points in the field of vision is now considered more correct. But he explained it in a 1 The original of this memoir was the successful essay submitted in com- petition for the Syme Surgical Fellowship in April 1884. Boforo publication it lias been revised and enlarged. * It is now located in a theoretical fusion centre. I. Introductory Sketch.