This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 Excerpt: ...fixation point in the visual field is moving. To obtain a definite answer to this, the further question (of great importance to optics and the theory of knowledge) must be considered: how it comes about that in the movement of the eye, owing to which the light impression varies constantly at each point of the retina, ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 Excerpt: ...fixation point in the visual field is moving. To obtain a definite answer to this, the further question (of great importance to optics and the theory of knowledge) must be considered: how it comes about that in the movement of the eye, owing to which the light impression varies constantly at each point of the retina, our inference should be that in spite of this variation of all the luminous impressions there is no displacement nor alteration of the object, but only a motion of the eye; it is obviously sufficient if this inference obtains for infinitely small displacements of the eye. But in order to convince ourselves that every alteration of the image upon all points of the retina collectively depends on the altered position of the eye alone, and not on any change of the object in the field of vision, we must fulfil the condition in virtue of which the transition of any point of the image from the retinal fovea to a definite point on the retina at infinitesimal distance, can only occur by rotation round a given axis, which is unalterable relatively to the eye. It follows from the law of simplest orientation and from the well-known theorem of mechanics, according to which the axial directions of infinitely small revolutions are compounded by the law of the parallelogram of forces, that the movement of the point of fixation to any second point of the visual field at infinitely small distance, must be caused by its revolution round an axis lying in a given plane, which is unalterable in relation to the eye. Now since the axes of rotation for all the movements which occur lie in one plane, no infinitely small rotation of the eye can produce a rotation of the same round the line perpendicular to this axial plane, which Helmholtz terms the atropic line of the e...
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Add this copy of Hermann Von Helmholtz to cart. $5.42, good condition, Sold by Midtown Scholar Bookstore rated 5.0 out of 5 stars, ships from Harrisburg, PA, UNITED STATES, published 1965 by Dover Publications.
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