The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 386 PHYSIOLOGICAL PHYSICS. [Chap. xxix. the base of the triangle is a little window, just above a in the figure, projecting vertically upwards, in which is a needle point. Di- rectly opposite, in the truncated apex of the triangle, is an opening through which the eye to be observed looks. The person at this opening is directed to look across through the window a, as if to a
The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 386 PHYSIOLOGICAL PHYSICS. [Chap. xxix. the base of the triangle is a little window, just above a in the figure, projecting vertically upwards, in which is a needle point. Di- rectly opposite, in the truncated apex of the triangle, is an opening through which the eye to be observed looks. The person at this opening is directed to look across through the window a, as if to a far-off object. At one of the angles of the triangular box are placed two prisms b and 6', in front of which a candle is Fig. 174.—The Pimko- placed, the lisjlit from which is scope of Helmholtz. 7, 1 , i '' ' • • j i i thrown by the prisms in the ob- served eye. The observer looks through the opening at o towards the eye to be observed, on which he sees three images, being images of the candle flame. They are reflected images ; the first is large, bright and upright (a, Fig. 175), a virtual image, the reflection from the surface of the cornea acting as a convex mirror ; the second image b is larger and erect, but dim. It is the reflection from the anterior surface of the lens, a virtual image also. The third image c is small, inverted, and still dimmer, a real inverted image from the posterior surface of the lens, actino- as a concave mirror. Now
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