A New and Complete Epitome of Practical Navigation; Containing All Necessary Instructions for Keeping a Ship's Reckoning at Sea, with the Most Approved Methods of Ascertaining the Latitude and the Longitude Including a Journal of a

A New and Complete Epitome of Practical Navigation; Containing All Necessary Instructions for Keeping a Ship's Reckoning at Sea, with the Most Approved Methods of Ascertaining the Latitude and the Longitude Including a Journal of a

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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. 1805 edition. Excerpt: ...what M. Borda calls cross observaTions, to the right and left successively; which indeed appears to be one of the principal reasons why those instruments have not been generally used. On the other hand, the practice of lie Sextant is subject to considerable conveniences, besides being liable to the above errors. For example, when a set of lunar stances is taken, it is necessary to read oil' the distance after eajch observation; which not only consumes lime and gives trouble, particularly at night, but disturbs the focus of the eye, so that the next observaHbn cannot be made so well or so readily as if no such interruption had taiten piace. In contriving the present Circle, Capt. Mendoza Rios's object has been to conibiue the advantages of multiplying, or finding at last the sum of all the measured distances, with the simple manner of observing with the Sextant; to which advantages may be adJed the diminution of the errors of division; although this last was not principally in view, as, since the invention of machines for dividing instruments, that advantage is not so important as it was some years ago; although it is certainly not to be neglected at present. The following short description of the new reflecting Circle will be sufficient to give an idea of the means, by which the combination of the above advantage? have been effected, and will shew the manner in which the instrument is to be used. The moveable circle, or limb a, (Fig. 2, Plate IX.) turns round under the frame of the instrument b, to which it is pressed by the clamps c; the index d is moveable on the axis of the frame, and has aniidjusting screw attached to it in the usual manner: on the 'frameThere is fixed a piece of brass e, which we shall call the stop, because the index may...show more

Product details

  • Paperback | 170 pages
  • 189 x 246 x 9mm | 313g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236635841
  • 9781236635846