Matter, Ether, and Motion

Matter, Ether, and Motion

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 edition. Excerpt: ... seconds, and then turns his eyes to a dimly lighted drab surface, he will be able to see, sometimes in a surprisingly realistic way, the same object against the new background. If it be a person looked at, the features may even appear in a startling way. The size of the subjective figure will depend upon the distance of the background, being larger the more remote that is. Age and health have much to do with the persistence of such sensations. Young and vigorous persons seldom notice them until they carefully look for them; while older ones, and especially weakened ones, may be much troubled by them. Some nervous systems react upon the eye itself, and give rise to similar images there; and these subjective images have not unfrequently been mistaken for objective persons living or dead. The color a given object appears to have is not unfrequently modified by what colors the eye has been resting upon the instant before, and hence two persons may look at once upon the same picture and see it in very different tints. As ether waves are the source of the sensation, it is obvious that a certain number of consecutive waves must be necessary to affect the eye; that is to say, it is not in the least probable that a single wave of any length could produce a sensation. How many are needed is not known, but one can determine somewhere near what the number must be if he knows how brief a time is sufficient to produce a sensation. It is said that some flashes of lightning have been found to occur in less than a millionth of a second, and those may produce a very strong sensation. If there are five hundred million million vibrations per second, as we know there must be to give such a sensation, in the millionth of a second there must be five hundred...show more

Product details

  • Paperback | 84 pages
  • 189 x 246 x 4mm | 168g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 123687062X
  • 9781236870629