A Manual of Spherical and Astronomy; Embracing the General Problems of Spherical Astronomy, and the Theory and Use of Fixed and Portable Astronomical Instruments. with an Appendix on the Method of Least Squares Volume 2

A Manual of Spherical and Astronomy; Embracing the General Problems of Spherical Astronomy, and the Theory and Use of Fixed and Portable Astronomical Instruments. with an Appendix on the Method of Least Squares Volume 2

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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. 1864 edition. Excerpt: ...to Art. 46 or 47. It is now evident that when the telescope is directed upon a star, if the micrometer reading remains M0 while the thread bisects the star and the circle reading is C," the nadir distance is C--C, precisely as if the micrometer thread were fixed. But the reading C" will, in general, involve an error of runs, to avoid which, set the circle as before upon a neighboring exact division, and let the reading be still called C"; then bisect the star with the micrometer thread, and let the reading be M'; the nadir distance of the star will be In practice, this method will be found much simpler than it at first appears. The finder should always be adjusted so that whole minutes in its reading correspond to whole minutes of the principal circle. Then, in all observations of the nadir point, we set the finder to the same exact division; and, in observing the star, we compute its approximate nadir distance to the nearest minute, and set the finder upon this minute. In the above formula, we suppose the micrometer readings to increase with the circle readings. Example.--On May 4, 1856, the telescope of the Meridian Circle of the Naval Academy was directed to the nadir by setting the finder upon 0 0', and the mean of the four microscopes gave the circle reading C0 = 359 59' 54."70 (or--0 0' 5."30) The micrometer thread was then brought alternately north and south of its own image in the collimator, so as to form each time a square with the middle transit thread and its image (as in Art. 147), and the micrometer readings were as follows: so that M0 was the reading when the micrometer thread was in coincidence with its image. The telescope was then directed to Polaris at its upper culmination by setting the...show more

Product details

  • Paperback | 160 pages
  • 189 x 246 x 9mm | 299g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236572416
  • 9781236572417