Wells's Natural Philosophy: For the Use of Schools, Academies, and Private Students

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American Book Company, 1879 - 510 pages
 

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Page 113 - All the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come, thither they return again.
Page 289 - The development of vegetation is greatest in tropical countries, and a great part of the nocturnal cooling is due to the leaves, which present to the sky an immense number of thin bodies, having large surface, well adapted to radiate heat.
Page 473 - A piece of zinc as large as a pea, or the point of a small iron nail, were found fully adequate to preserve forty or fifty square inches of copper ; and this, wherever it was placed, whether at the top, bottom, or in the middle of the sheet of copper, and whether the copper was straight or bent, or made into coils. And where the...
Page 358 - If the objects of the material world had been illuminated with white light, all the particles of which possessed the same degree of refrangibility, and were equally acted upon by the bodies on which they fall, all nature would have shone with a leaden hue; and all the combinations of external objects, and all the features of the human countenance, would have exhibited no other variety than that which they possess in a pencil sketch or...
Page 1 - A grain of musk has been kept freely exposed to the air of **• a room, of which the door and windows were constantly...
Page 31 - ... of gravity. If the two bodies be of equal weight, the centre of gravity will be in the middle of the line which unites them. But if one be heavier than the other, the centre of gravity will be as much nearer to the heavier one as the heavier exceeds the light one in weight.
Page 39 - When a man walks at a moderate rate, his centre of gravity comes alternately over the right and over the left foot. This is the reason why the body advances in a waving line, and why persons walking arm in arm shake each other, unless they make the movements of their feet to correspond, as soldiers do in marching.
Page 137 - Tbe loss of weight in water, 5 ounces, is the weight of a bulk of water equal to that of the body.
Page 241 - ... it meets a reflecting surface, from which it rebounds in another straight line, the direction of which is determined by the law that the angle of incidence is equal to the angle of reflection. The manner in which heat is reflected is strikingly shown by taking two concave mirrors, Hand N, Fig.
Page 63 - 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.

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