Transactions of the Royal Society of Edinburgh Volume 15

Transactions of the Royal Society of Edinburgh Volume 15

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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. 1844 edition. Excerpt: ...direction. 7. On the Vision of Cameos aml Intaglios. The beautiful experiment of converting a cameo into an intaglio, and an intaglio into a cameo, by monocular vision, is well known. In 1825 I had occasion to investigate this subject, and in January 1826 I published an account of my observations, with an ample notice of the previous labours of other authors. Mr WHEATSTONE has ingeniously connected this optical fallacy with the union of dissimilar images on the retina, though he does not refer it to this union as its cause. After quoting my previous explanation of the illusion, he makes the following observations upon it. " These considerations do notfully explain the phenomenon, for they suppose that the image must be inverted, and that the light must fall in a particular direction; but the conversion of relief will still take place when the object is viewed through an open tube without any lenses to invert it, and also when it is equally illuminated in all parts."+ In thus objecting to the falness of my explanation, Mr WHEATSTONE has overlooked the great number of experiments by which I have supported it; and especially those facts in which I observed the fallacy when the object is viewed without even an open tube, without inversion;--with both eyes open, and when it is placed in broad daylight. Mr Wnnxrsroxn then gives his own opinion as follows. "If we suppose a cameo and an intaglio of the same object, the elevations of the one corresponding exactly to the depressions of the other, it is easy to shew that the projection of either on the retina is sensibly the same.i When the cameo or the intaglio is seen with both eyes, it is impossible to mistake an elevation for a depression; but when either is seen by one eye...show more

Product details

  • Paperback | 310 pages
  • 189 x 246 x 17mm | 558g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236883721
  • 9781236883728