Elementary Treatise on OpticsBarnes, 1848 - 259 páginas |
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Términos y frases comunes
aberration achromatic angle of incidence aperture arcs axis beam called centre coincide concave consequently considered converging convex convex lens crown glass crystal dark denoting determined deviation diminishes direction dispersive powers distance of distinct distinct vision diverging double refraction elementary rays emanating emerge equal equation ether evidently extraordinary ray eye-glass flint glass foci formed fringes glass greater hence incident ray indices of refraction intensity length lens lenses less luminous point magnified maximum medium mirror molecules oblique optic optic axis ordinary ray parallel pencil of light perpendicular plane of incidence plane of polarization plate polarized light position primary colors principal focal distance principal focus principal section prism produced propagated reflected rays refracting angles retina right angles rings screen semi-undulation sensibly spherical spherical aberration straight line stripes substances supposed tang telescope thickness tion tourmaline undulations unpolarized varies velocity vibration whilst
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Página 170 - 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...
Página 152 - Almost all scientific men, at the present day, believe that the particles of a luminous body are in a state of...
Página 235 - ... 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...
Página 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.
Página 130 - ... 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...
Página 95 - Achromatic Lenses. The color effect caused by the chromatic aberration of a simple lens greatly impairs its usefulness.
Página 115 - 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.
Página 188 - ... transmitted rings were found to observe the same laws, — with this remarkable exception, that the colour transmitted at any particular thickness of the plate was always complementary to that reflected at the same thickness ; so that in homogeneous light, the bright transmitted ring is always found at the same distance from the centre as the corresponding dark one of the reflected system. The observations of Mariotte*, Mazeast, and DutourJ have added nothing essential to the laws discovered...
Página 152 - ... the sensation of light ; in a manner analogous to that in which the vibrations of the air, striking upon the tympanum of the ear, produce the sensation of sound.