Transactions Volume 4-5

Transactions Volume 4-5

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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. 1882 edition. Excerpt: ...the direction to the newly determined point measured. The value obtained corresponds approximately to the magnetic declination at Ino's time, as illustrated in Fig. 2, explained as follows: --I, direction given by Ino. P, new position of peak. /3, angle given by Ino (small correction applied)., angle measured from map, between newly determined direction and true meridian (true azimuth of direction to peak P, determined approximately by mapping). D, direction of magnetic meridian at Ino's time. Y = /S--a = approximate declination at Ino's time. 5. All those field sketches forming a connection between two stations contained in Ino's map were put together, the straight distance of the stations and the magnetic azimuth of the connecting line were measured, and the results obtained compared with the corresponding lengths and angles in Ino's map. Though the differences of direction procured in this way can not be used for ascertaining the former magnetic variation at the single localities, it is worth notice that the average of the deviation from Ino's directions very nearly corresponds to the probable average increase of the declination since Ino, as derived by application of the methods mentioned before. Before commencing a discussion of the tables and of the curves shown on the accompanying map of Japan, I have to remark t hat the error of the prismatic compass which I made use of, has not yet been determined sufficiently, and that the graphic exhibition of my results can only be taken as a rough sketch. Most likely it was first at Tokio that Ino was led to the conviction of the great exactitude of his compass on account of its constantly pointing to the true North. For this reason it must be of special interest to measure more

Product details

  • Paperback | 66 pages
  • 189 x 246 x 4mm | 136g
  • United States
  • English
  • black & white illustrations
  • 1236769651
  • 9781236769657