Elements of Natural Philosophy, Volumes 2-3

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Page 172 - When a ray of light passes from one medium to another, it is refracted so that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the velocities in the two media.
Page 333 - ... o", will be double -eo. If either or both of the component waves whose directions are e e', and o o', had been polarized by reflexion, refraction or absorption, the action of the second prism would have been the same ; this is, therefore, another characteristic property of plane polarized light, viz. : that it will not undergo double refraction when its plane of polarization is either parallel or perpendicular to the plane of...
Page 116 - C fork), by means of the movable stopper or card, or the fork may be loaded till the unison is perfect. Then set the fork in vibration by a blow on the unloaded branch, and hold the card closely over the mouth of the pipe, as in the engraving, when a note of surprising clearness and strength will be heard. Indeed, a flute may be made to
Page 336 - ... in the plane of principal section, and the other in a plane perpendicular to it. Each of these must be again resolved, in two fixed directions which are also perpendicular; and it will easily appear from the process of resolution, that, of the four components into which the original vibration is thus resolved, the...
Page 47 - For every 11090 feet of distance, the pull, push, or blow, will reach its point of action one second after the moment of its first emanation from the first mover. In all moderate distances, then, the interval is utterly insensible. But were the sun and the earth connected with an iron bar, no less than 1074 days, or nearly three years,* must elapse before a force applied at the sun could reach the earth.
Page 324 - The product of radius and the cosine of the sum of two arcs, is equal to the product of the cosines of the arcs — the product of their sines.
Page 91 - Dionysius isEarofDion celebrated in ancient history ; it was a grotto cut out of the solid rock at Syracuse, in which a person placed at one point could hear every word, however faintly uttered, in the grotto. It was doubtless of a parabolic shape. The same principle is employed in the construction of Speaking Tubes, used for the purpose of communicating between different apartments of the same building, DOW coming into very general use.
Page 95 - ... variety in the modes of aerial vibration, and the astonishing acuteness and delicacy of the ear, thus capable of appreciating the minutest differences in the laws of molecular oscillation. All mere noises are occasioned by irregular impulses communicated to the ear ; and, if they be short, sudden, and repeated beyond a certain degree of quickness, the ear loses the intervals of silence, and the sound appears continuous.
Page 107 - ... finger, or a feather, exactly in the middle or at one-third of its length, from either end, it will not cease to vibrate, but its vibrations will be diminished in extent and increased in frequency, and a note will become audible, more faint but more acute than the original, or fundamental note, as it is called, and corresponding, in the former case, to illustrated by the a double, and in the latter, to a triple rapidity of vibravionn; tion.
Page 305 - To remedy this defect, achromatic lenses were formed by the union of a convex lens of crown glass with a concave lens of flint glass.

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