A Mode of Motion

A Mode of Motion

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 edition. Excerpt: ...half filled with water, the upper surface of which cuts the tube in two equal parts horizontally. Thus, half of the beam is sent through air, and half through water, and with this lens, c, a magnified image of the adjacent end of the tube is projected on the screen. You now see the image, o P, composed of two semicircles, one of whioh is formed by the light which has passed through the water, the other the light which has passed through the air. Placed thus, side by side, you can compare them, and you notice that, while the air semicircle is a pure white, the water semicircle is a bright and delicate blue-green. Thus, by augmenting the thickness through which the light has to pass, we deepen the color; this proves that the destruction of the light-rays takes place within the absorbing body, and that it is not an effect of surface merely. (356) Melloni shows the same to be true of radiant heat. In his experiments, already recorded at page 262, the thickness of the plates used was 2-6 millimetres, but, by rendering the plate thinner, we enable a greater quantity of heat to get through it, an., by rendering a very opaque substance sufficiently thin, we may almost reach the transmission of rocksalt. The following table shows the influence of thickness on the transmissive power of a plate of glass: (357) Thus, we see that, by diminishing the thickness of the plate from 2-6 to 0-07 millimetres, the quantity of heat transmitted rises, in the case of the lamp of Locatelli, from 39 to 77 per cent.; in the case of the incandescent platinum, from 24 to 57 per cent.; in the case of copper at 400 C, from 6 to 34 per cent.; and in the case of copper at 100 0., from absolute opacity to a transmission of 12 per cent. (358) The influence of the thickness of a...show more

Product details

  • Paperback | 166 pages
  • 189 x 246 x 9mm | 308g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236513614
  • 9781236513618