An Elementary Treatise on Optics

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G.Y. Van Debogert, 1852 - Optics - 261 pages
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Page 31 - ... that the ratio of the sines of the angles of incidence and refraction is constant for refraction in the same medium, was effected by Snell and Descartes.
Page 172 - COLOURS, Length of an Undulation in parts of an inch in Air. Number of Undulations in an inch. Number of Undulations in a second. Extreme...
Page 154 - Almost all scientific men, at the present day, believe that the particles of a luminous body are in a state of...
Page 240 - ... their planes of polarization are at right angles to one another ; hence, a pile of panes of glass will give a polarized beam by refraction. For if a ray of common light pass through them, part of it will be polarized by the first...
Page 30 - When a ray of light passes from one medium into another, it usually traverses it with a change of direction. But the respective densities of the two media may be such that, for a given angle of incidence, refraction is no longer possible.
Page 132 - ... mirror, which, if the aperture be sufficiently large, may be viewed directly by means of an eye-piece placed in a suitable position, as in the case of the telescopes previously described. Such is the principle of Sir W. Herschel's telescope, which is the simplest of the reflecting telescopes. In order that the head of the observer may intercept as little light as possible, the axis of the mirror is slightly inclined to the axis of the tube in which it is fixed, and thus the image is thrown near...
Page ii - Entered according to Act of Congress, in the Office of the Clerk of the Northern District of the State of New- York, August, 1852.
Page 111 - ... the white letters will appear larger, and be read at a greater distance, than the black. This is owing to what is called the irradiation of light. It depends on this, that the impression made on the bottom of the eye by bright objects extends a little wider than the actual portion of...
Page 71 - No. 768 deviation of a ray passing through a prism in a principal plane is a minimum when the angles of incidence and emergence are equal ( 134) is much more elegant than any we have seen before.
Page 117 - R'EW' nearly as RW to R'W'; so that the visual angle is enlarged in the ratio of the distance of distinct vision to the focal length of the lens. A convex lens, from the property it possesses of enlarging the apparent size of objects, is called a magnify ing-glass or a single microscope.

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