Elements of Natural Philosophy

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J. Churchill, 1848 - Physics - 552 pages
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Page xliii - To this purpose the philosophers say that Nature does nothing in vain, and more is in vain when less will serve; for Nature is pleased with simplicity, and affects not the pomp of superfluous causes.
Page xliii - The qualities of bodies, which admit neither intension nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever.
Page 136 - Impenetrability, — which signifies that no two bodies can occupy the same space at the same time.
Page xliii - In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions. This rule we must follow, that the argument of induction may not be evaded by hypotheses.
Page 140 - ... of the whole quantity of matter in the earth. But the attraction of a quantity of matter at the earth's centre would be more powerful on a body at the bottom of a mine than on one at the top, in the inverse ratio of the squares of the distances of the bodies from the earth's centre : that is in the present case in the ratio of four to one. Hence the attraction on a body at the bottom of the mine would be, on the whole, less than the attraction on a body on the top in the ratio of one to two.
Page 345 - He assumed that all animals are endowed with an inherent electricity appropriate to their economy, which electricity, secreted by the brain, resides especially in the nerves, by which it is communicated to every part of the body. The principal reservoirs of this electricity he considered to be the fibres of muscles, each of which he regarded to have two sides in opposite electric conditions. He believed that when a...
Page 40 - 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.
Page 397 - B, which is in the red near the end of the spectrum ; c is farther advanced in the red ; D is in the orange ; E, in the green ; F, in the blue ; G, in the indigo ; and H, in the violet.
Page 216 - ... the earth by a wire or chain : on turning the cylinder, the bells A and B become positively electrified, and by induction the central one becomes negative; luminous discharge taking place between them, if the electricity be in too high a state of tension. But if the cylinder be slowly revolved, the little brass clappers will become alternately attracted and repelled by the outermost and inner bells, producing a constant ringing as long as the machine is worked.
Page 124 - The jet from B, for instance, has the same velocity as if the particles composing it had fallen in vacuo from H to B.

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