Elements of Acoustics, Light, and HeatG.P. Putnam's Sons, 1873 - 140 páginas |
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Términos y frases comunes
absorbed aërial angle of incidence aperture appears aqueous vapour atmosphere beam becomes boiling point bulb called candle carbonic acid cold colder colour combustion concave concave lens condensed converge convex lens cooled crystalline lens cubic cubic foot density diathermic diminishes distance diverging double convex lens effect elasticity equal evaporation experiment Fahrenheit fall feet fire flame formed gases gives glass glottis greater hence hydrogen intensity inversely iron latent heat latter length liquid luminous mercury metallic mirror motion musical sound number of vibrations object ordinary particles pass perpendicular pitch pressure principal focus prism produced propagated quantity radiant heat ray of light reflection reflector refraction retina rock-salt screen seen sensation solid sonorous wave sound-wave specific heat spectrum spherical spherical aberration spherical reflector steam string substance surface takes place temperature tion transmitted transparent tube velocity of sound vessel warm whilst white light
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Página 108 - The heat which is expended in changing a body from the solid to the liquid state, or from the liquid to the gaseous state, is called latent heat.
Página 127 - Remove for a single summer-night the aqueous vapour from the air which overspreads this country, and you would assuredly destroy every plant capable of being destroyed by a freezing temperature. The warmth of our fields and gardens would pour itself unrequited into space, and the sun -would rise upon an island held fast in the iron grip of frost.
Página 127 - No doubt, therefore, can exist of the extraordinary opacity of this substance to the rays of obscure heat ; and particularly such rays as are emitted by the earth after it has been warmed by the sun.
Página 66 - In a word, the greater the distance of the object the smaller the image. The angle AOB is called the visual angle; in general, it is the angle which the object subtends at the centre of the crystalline lens. It thus appears that, so far as the eye is concerned, the size of an object depends upon the magnitude of the visual angle. If, therefore, we have any number of objects, A, B, C, etc. (fig.
Página 75 - It is to be borne inmind that bodies of all colours, illuminated by white light, reflect white light from their exterior surfaces. It is the light which has plunged to a certain depth within the body, which has been sifted there by elective absorption, and then discharged from the body by interior reflexion that, in general, gives the body its colour.
Página 99 - ... rush in to fill their place. There are, therefore, permanent atmospheric currents established from the poles towards the equator. These, combined with the effects of the rotation of the earth upon its axis, produce the phenomena called the trade-winds, which blow with such regularity and permanency, in the northern hemisphere from the north-east, and in the southern hemisphere from the south-east. It must be observed, however, that the sun is not the only cause which affects the temperature of...
Página 108 - The vast influence which the ocean* must exert as a moderator of climate here suggests itself. The heat of summer is stored up in the ocean, and slowly given out during the winter. Hence one cause of the absence of extremes in an island climate.
Página 38 - The disciples of Plato contributed not a little to the advancement of optics, by the important discovery they made, that light emits itself in straight lines, and that the angle of incidence is always equal to the angle of reflection. Plato terms colours " the effect of light transmitted from bodies, the small particles of which were adapted to the organ of sight" This seems precisely what sir Isaac Newton teaches in his " Optics,
Página 76 - The color of light depends on the number of ethereal waves which strike the eye in a second. Thus the sensation of red is produced by imparting to the optic nerve four hundred and seventy-four millions of millions of impulses per second, while the sensation of violet is produced by imparting to the nerve...
Página 52 - It is the frequency of the reflexions at the limiting surfaces of air and water that renders foam opaque. The blackest clouds owe their gloom to this repeated...