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All Necessary Instructions for Keeping a Ship's Reckoning
WITH THE MOST APPROVED METHODS OF ASCERTAINING THE
LATITUDE AND LONGITUDE,
AND EVERY REQUISITE TO FORM
THE COMPLETE NAVIGATOR;
THE WHOLE BEING RENDERED PERFECTLY EASY, AND ILLUSTRATED BY
NUMEROUS EXAMPLES, DIAGRAMS AND CHARTS.
Rearranged and Considerably Extended.
By J. W. SAUL.
D. VAN NOSTRAND COMPANY
HAVING been for several years past engaged in the instruction of persons designed for, or belonging to the Sea, I have frequently had occasion to lament that most of the existing works on Practical Navigation, and particularly some that have been very generally circulated, are extremely erroneous, both in the instructive and tabular parts, and by no means calculated to answer all the purposes of the Mariner, Teacher, or Pupil.
With a view to remedy these defects, and to facilitate the acquirement of this most important art, and further stimulated by the flattering reception of my former labours, I have ventured to exert my best abilities in composing the present work ; and, although I do not mean to arrogate to myself any superior professional merit, yet I humbly apprehend that my long experience and intimate connection with the subject have enabled me, in some measure, to form a competent judgment of what is most requisite to assist the industrious Mariner in acquiring a knowledge of the practical part of Navigation.
In order to accomplish my intended purpose as effectually as possible I have examined, with the greatest attention and on, the various publications that have been written on Navigation, and placing them in a comparative point of view, have, I trust, been thence enabled to avoid the errors, and to improve the merits, of those who have preceded me in this branch of Science.
That nothing might be wanting to assist the student in his progress through the subject, I have commenced with a short treatise on Decimal Arithmetic, the nature of which he will find very necessary to be understood in going through the various computations that follow. Geometry such definitions and problems only are introduced as appear most essential. Plane Trigonometry, both right and oblique-angled, being the foundation of the Sailings, is treated of at considerable length. Next follows Geography, containing a description of the form and magnitude of the Earth, with its various real and imaginary divisions, and an explanation of the nature of latitude and longitude: an account is then given of the Instruments used for measuring a Ship’s way, with the manner of correcting their errors. This finishes the introductory part to Navigation.
We now proceed to the various Sailings in which the examples are resolved by construction, calculation, inspection and Gunter's Scales; then