Six Lectures on Light Delivered in America in 1872-1873

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D. Appleton, 1901 - Light - 272 pages
 

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Page 108 - Newton is that every particle of matter, of every kind, attracts every other particle with a force varying as the inverse square of the distance. In virtue of the attraction of gravity, then, the magnets, if perfectly free to move, would slowly approach each other. But besides the unpolar force of gravity, which belongs to matter in general, the magnets are endowed with the polar force of magnetism. For a time, however, the polar forces do not come sensibly into play. In this 1 In a little volume...
Page 51 - was one of the most profound that the world has ever produced ; but he had the misfortune of being too much in advance of his age. He excited the wonder of his contemporaries, who, however, were unable to rise to the heights at which his daring intellect was accustomed to soar. His most important ideas lay, therefore, buried and forgotten in the folios of the Royal Society, until a new generation gradually and painfully made the same discoveries, proving the truth of his assertions and the exactness...
Page 151 - But the phenomena become more numerous, more various, more strange; no matter : the Theory is equal to them all. It makes not a single new physical hypothesis ; but out of its original stock of principles it educes the counterpart of all that observation shows. It accounts for, explains, simplifies, the most entangled cases ; corrects known laws and facts ; predicts and discloses unknown ones ; becomes the guide of its former teacher, Observation ; and, enlightened by mechanical conceptions, acquires...
Page 63 - ... are of intermediate pitch or wave-length. The length of a wave of the extreme red is such that it would require 36,918 of them, placed end to end, to cover one inch, while 64,631 of the extreme violet waves would be required to span the same distance. Now, the velocity of light, in round numbers, is 190,000 miles per second. Reducing this to inches, and multiplying the number thus found by 36,918, we...
Page 115 - Now, in the case of a plate of tourmaline cut parallel to the axis of the crystal...
Page 13 - ... is convex or concave, whether the stars are fixed in the sky or float freely in the air; of what size and of what material are the heavens; whether they be at rest or in motion ; what is the magnitude of the earth; on what foundations it is suspended and balanced ;—to dispute and conjecture on such matters, is just as if we chose to discuss what we think of a city in a remote country, of which we never heard but the name.
Page 232 - Rumford, and Rittenhouse, and Davy, and Faraday, and Henry. Is it not evident that Nature herself, to those who will follow her teachings, is a better guide to the study of her own phenomena than all the training of our schools ? And is not this because Nature invariably begins with the training of...
Page 221 - Thus, before your practical men appeared upon the scene, the force had been discovered, its laws investigated and made sure, the most complete mastery of its phenomena had been attained — nay, its applicability to telegraphic purposes demonstrated — by men whose sole reward for their labors was the noble excitement of research, and the joy attendant on the discovery of natural truth.
Page 241 - ... truth safe in every line of investigation ; next, infidelity, by which I do not mean want of fidelity to this or that dominant creed, but want of fidelity to that which underlies all creeds, the idea that the true and the good are one ; and, finally, materialism, by which I do not mean this or that scientific theory of the...
Page 218 - Is this exhibition of energy the work of the muscles alone? By no means. The muscle is the channel of an influence, without which it would be as powerless as a lump of plastic dough. It is the delicate unseen nerve that unlocks the power of the muscle.

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