Researches Volume 3

Researches Volume 3

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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. 1917 edition. Excerpt: ...(a) The compass magnets are solid bars of tungsten steel, carefully magnetized by the methods used for the magnets of the Department's land magnetometers; (6) the matter of centering and mounting of the compass magnets is executed with special regard to accurate adjustment and balancing of magnet-system; (c) the lubber-lines are in black on the polished-silver reflecting surface; (d) the surface of the graduated German-silver circle is in the same plane as the pivot point (in No. 4 this plane is 1.7 mm. above the pivot point); (e) the filling cap is on the side instead of below, as is the case in No. 4, thus making it possible, in emergency, to fill the bowl without removing either deflecting-magnet standard; (J) two sliding shades have been provided for the sighting vane L2; (g) the sighting vane LI has been provided with arrangements for two slides, one for the pianoparallel glass with reference line, and the other for the color-glass shade; (h) the vertical ground-glass pieces with reference lines for the azimuth work are mounted by clamps instead of, as in No. 4, by screws, thus permitting a more permanent adjustment, and eliminating the danger of breakage occasioned by drilling of glass plates; (i) the line of reference on the cover plate is white instead of black, as for No. 4. (For views of No. 5, see Pl. 13.) Scheme Of Horizontal-intensity Observations. In the following scheme of observations for horizontal intensity, the deflection distances, in the order of increasing magnitude, are designated for the upper standard as Ul, U2, U3, and U4; for the lower standard they are similarly, LI, L2, L3, and L4. For distances 1 and 3, the sight line is L2 to 180 and L2 to 0, and for distances 2 and 4, L2 to 270 and L2 to 90. Observations...show more

Product details

  • Paperback
  • 189 x 246 x 10mm | 327g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236913590
  • 9781236913593