Scientific American; Supplement Volume 20

Scientific American; Supplement Volume 20

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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. 1885 edition. Excerpt: the unaided eye, how vastly superior in accuracy is the photograph of t hose requiring considerable magnifying power to render their structure visible? The most perfect drawing made under the camera lucida will be found more or less diagrammatic, while two or more drawings of the same subject, made by different artists of equal skill, will differ materially; each one penciling what he seesor thinks he sees. The sensitive plate, being incapable of feeling or thinking, records only the impression reflected upon it, and thus gives us an exact reproduction of the image formed by tne lens. The projecting lantern has been used for throwing transparencies upon a suitably prepared screen, but the subjects have usually been drawings, more or less diagrammatic and inaccurate. The desirability of using photographs made direct from the objects has been recognized, but the cost of the necessary apparatus, together with the time, labor, and skill required for its successful application, have prevented hitherto general adoption of this most perfect method of exhibiting a microscopical specimen to a class or audience of any kind. The universal application and use of photography, however, brought about by the introduction of gelatine dry plates, has changed all this. The cost of the necessary apparatus has een reduced to a minimum, while its bulk and complexity have followed suit. The stains and disagreeable odors, attendant upon the old silver bath and collodion processes, have been consigned to oblivion. The prepared dry plates are furnished to us of uniform quality, by reliable makers, at extremely low prices, and the whole processes of making both negatives and positives may be pleasantly accomplished of a winter's evening, without even more

Product details

  • Paperback | 874 pages
  • 189 x 246 x 44mm | 1,529g
  • United States
  • English
  • black & white illustrations
  • 123678250X
  • 9781236782502