Account of the Operations of the Great Trigonometrical Survey of India Volume 9

Account of the Operations of the Great Trigonometrical Survey of India Volume 9

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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. 1883 edition. Excerpt: ... obtains when the telescope is L.P. W. Now considering that if a wire is too far west, the image of a star will transit over it too soon, it is apparent that the formulae for the positions I.P.E. and I.P. W. must he cx = C0--Cs, and cx = Cs--C0, respectively. At least one determination of collimation error was made every night, and the value of cx obtained is the correction-constant for collimation for the night, by which the collimation correction for each star observed must be computed. In making these observations several readings of the collimators were taken by the telescope, and the precaution was followed of causing the telescope to oscillate--or wholly revolve--after each reading, varying the direction of its rotation. 4. Diurnal Aberration. The effect of the diurnal aberration on the time of a star's transit was not lost sight of, although for all the arcs measured--or indeed for any ever likely to be measured--that effect is inappreciable when the observations taken at both stations are combined. The correction for diurnal aberration is a constant quantity for each station, which, like that for collimation, must be multiplied by the secant of each star's declination to obtain the correction in time for that star's observed transit, hence the two corrections may be combined. The correction used for aberration was--, 207 x the cosine of the latitude, and this, converted into terms of the micrometer and applied to clf gave c, which was used as the correction-constant for collimation and aberration combined for each night. During season 1876-76, the quantity Cj was used as resulting from each night's observations, but in 1876-77 it was considered that the change of the line of collimation, while the telescope remained in...show more

Product details

  • Paperback | 58 pages
  • 189 x 246 x 3mm | 122g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236630076
  • 9781236630070