Sciography: Or, Radial Projection of Shadows

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Chapman and Hall, 1868 - Perspective - 50 pages
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Page 40 - ... atmosphere, and are diffused into that universal, soft light which we observe around us. REFLECTION adds to the brilliancy of the great mass of light transmitted from the sun. If all the objects on the surface of our planet were black, which is a negation of all color, the sun's light would be absorbed, and we should, even while the sun shone, possess much less light than we now enjoy. But, in consequence of the varied coloring in which our earth is dressed, the sun's rays are more or less reflected,...
Page 42 - 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,
Page 40 - ... reach of its rays. Thus, the surface of a smooth lake will represent the image of the sky above, or the neighbouring hills, or of any object floating on its surface. This natural property in clear surfaces has suggested the formation of mirrors or looking-glasses.
Page 41 - RE, and consequently parallel. In every position of the eye the image is íseen in the same spot ; its absolute size is always the same, and its apparent size is also the same when seen at equal distances from the eye. If the object MN is an individual surveying himself in the mirror, he will see his perfect image as if at mn.
Page 2 - No. 16. any common observation is concerned, light may be regarded as perfectly instantaneous in its action. Light proceeds in a straight direction from the luminous body which produces it, towards the part or situation against which it is permitted to act. In consequence of this directness, a shadow or darkened spot is observable behind any opaque object presented to the light. During night, we are in the earth's shadow; and this shadow reaches so far beyond us into space, that when the moon plunges...
Page 41 - D of the mirror so situated, with respect to the eye and the object, that the angles of incidence of the rays which fall on these portions must be equal to the angles of reflexion of those which enter the eye between F and G. The ray...
Page 41 - GH of the mirror, so situated with reference to the eye and the object, that the angles of incidence of the rays which fall on these portions must be equal to the angles of reflection of those which enter the eye between i and Jc.
Page 40 - We now, then, understand that every object we see reflects rays of light, and that these rays travel from the object to our eye, as soon as we bend our vision upon it : inasmuch, however, as a thousand or more individuals may see the same object at the same instant of time, it is evident that the rays emanate at all points, and fall upon eyes at every variety of angle. If the object "be clear or polished in its surface, it will possess the power of representing the image of objects whose rays fall...
Page 40 - ... see reflects rays of light, and that these rays travel from the object to our eye, as soon as we bend our vision upon it : inasmuch, however, as a thousand or more individuals may see the same object at the same instant of time, it is evident that the rays emanate at all points, and fall upon eyes at every variety of angle. If the object "be clear or polished in its surface, it will possess the power of representing the image of objects whose rays fall on it. Thus the surface of a smooth lake...

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