The Elements of Acoustics, Light, and Heat

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Longmans, 1871 - Heat - 186 pages

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Page 155 - The third specific difference is this; that heat is a motion of expansion, not uniformly of the whole body together, but in the smaller parts of it ; and at the same time checked, repelled, and beaten back, so that the body acquires a motion alternative, perpetually quivering, striving and struggling, and irritated by repercussion, whence springs the fury of fire and heat.
Page 156 - Heat is a motion, expansive, restrained, and acting in its strife upon the smaller particles of bodies. But the expansion is thus modified: while it expands all ways, it has at the same time an inclination upwards. And the struggle in the particles is modified also: it is not sluggish, but hurried and with violence.
Page 82 - ... that every ray of white light may be separated into seven primary colours : red, orange, yellow, green, blue, indigo, and violet — that the variegated colouring which appears on the face of nature is not in the objects themselves, but in the light which falls upon them — that the rainbow is produced by the refraction and reflection of the solar rays in the drops of falling rain — that the rays of light are refracted, or bent out of their course, when they fall upon glass, water, and other...
Page 116 - The same unanimity has not prevailed either as respects the unit or the thermometric zero. In England, Holland, some of the German States, and in North America, the interval between the freezing and boiling points is divided into 180 equal parts, each part representing the thermometric unit. The scale is continued by equal divisions above the boiling and below the freezing points. The zero is placed at the thirty-second division below the: freezing point ; so that, on this scale, the freezing point...
Page 119 - For a given pressure ebullition commences at a certain temperature, which varies in different liquids, but which, for equal pressures, is always the same in the same liquid. III. Whatever be the intensity of the source of heat, as soon as ebullition commences, the temperature of the liquid remains stationary.
Page 155 - ... which I will presently subjoin, as soon as I have added a few cautions for the sake of avoiding ambiguity Nor again, must the communication of heat, or its transitive nature, by means of which a body becomes hot when a hot body is applied to it, be confounded with the form of heat. For heat is one thing, and heating is another. Heat is produced by the motion of attrition without any preceding heat...
Page 59 - When light passes from any given medium into another, no matter what may be the angle of incidence, it always conforms to the following laws : 1. The planes of incidence and refraction coincide, both being normal to the surface separating the media, at the point of incidence. 2. The sine of the angle of incidence is equal to the sine of the angle of refraction multiplied by a constant quantity.
Page 179 - GENERAL INSTRUCTIONS. If the rules are not attended to, the paper will be cancelled. You may take the Elementary, or the Advanced, or the Honours paper, but you must confine yourself to one of them.
Page 176 - Eight questions are to be attempted: two in acoustics; three in light; three in heat. In all cases the number of the question must be placed before the answer on the worked paper. Three hours are allowed for this paper. 1 . The velocity of sound in water is much greater than its velocity in air ; why is this the case ? 2. You are required to express numerically the elasticity of the air on the top of a mountain as high as Mont Blanc, on the top of a mountain as high as Ben Nevis, and at the sea level...
Page 129 - WINDS. 620. Wind is air put in motion. The air is never entirely free from motion, but the velocity with which it moves is perpetually varying.

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