All the Year Round Volume 3; V. 23

All the Year Round Volume 3; V. 23

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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. 1870 edition. Excerpt: ... The night selected was dark and cloudless, the mountain was covered with snow, and a cold wind gushed across the wintry scene. Colby was on Davis Mountain, Drummond on Slieve Snaught; on tho instant the latter displayed his lime light, the former saw it as a brilliant star, shining over the intervening Lough Neagh. It was a complete success of a beautiful experiment. The light was produced by placing a small ball of lime, only a quarter of an inch in diameter, in the focus of a parabolic mirror, and directing upon it (through a flame arising from alcohol) a stream of oxygen gas; the lime became white hot, giving out a light, the intensity of which alike surpassed conception and description. It is literally true that a tiny bit of lime was visible sixty-six miles distant; for it was not flame that was seen, but the actual white-hot lime itself. The experiment having once succeeded, it was applied in various ways. One of the famous triangles established by Colonel Colby had for its three points Ben Lomond in Dumbartonshire, Cainsmuir in Kirkcudbrightshire, and a mountain in Antrim in Ireland; each station was rendered, by the lime light, visible from each of the other two, although the distances were sixty-seven, eighty-one, and ninety-five miles respectively. On another occasion he even exceeded a hundred miles, by this wonderful light. The ordnance surveyors have also succeeded in rendering their far distant stations visible in the day-time, by a peculiar employment of sunlight. Small pieces of polished tin, speculum metal, silvered copper, or looking-glass, are so fixed in apparatus, that the sun's rays may be reflected in a line leading to the distant station, where a telescope renders the ray visible. Little gleams of sunshine have thus more

Product details

  • Paperback | 490 pages
  • 189 x 246 x 25mm | 866g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236617800
  • 9781236617804