American Practical Navigator An Epitome of Navigation and ORIGINALLY BY NATHANIEL BOWDITCH, LL. D. PUBLISHED AND SOLD BY THE UNITED STATES HYDROGRAPHIC OFFICE UNDER THE AUTHORITY OF THE SECRETARY OF THE NAVY £7 1920 STATUTES OF AUTHORIZATION. There shall be a Hydrographic Office attached to the Bureau of Navigation in the Navy Department, for the improvement of the means for navigating safely the vessels of the Navy and of the mercantile marine, by providing, under the authority of the Secretary of the Navy, accurate and cheap nautical charts, sailing directions, navigators, and manuals of instructions for the use of all vessels of the United States, and for the benefit and use of navigators generally. (R. S. 431.) The Secretary of the Navy is authorized to cause to be prepared, at the Hydrographic Office attached to the Bureau of Navigation in the Navy Department, maps, charts, and nautical books relating to and required in navigation, and to publish and furnish them to navigators at the cost of printing and paper, and to purchase the plates and copyrights of such existing maps, charts, navigators, sailing directions, and instructions, as he may consider necessary, and when he may deem it expedient to do so, and under such regulations and instructions as he may prescribe. (R. S. 432.) 2 'BRARY NOTE ON REPRINT OF 1919.-All typographical or other errors, so far discovered, have been corrected in this edition. There has been introduced at the foot of Table 2 a panel of headings, enabling the user to see at a glance the interchanges of the designations of the different columns of the table in order to subserve the various uses for which it is adapted in Plane, Middle Latitude, and Mercator Sailing, and in the general solution of plane right-angled triangles. Article 274, on the subject of Mean Time, and article 332, on the subject of finding the Latitude by a single Altitude at a given time, have been revised. The Knot as a measure of speed has been defined in article 10, and Leeway has been defined in a footnote to page 84. The application of the Haversine table, No. 45, to the solution of the Time Sight has been explained in articles 319 and 343, and to the solution of AltitudeAzimuth in article 355. Misunderstandings having arisen regarding the paging of this book, the reader is advised that the consecutive page numbering is purposely interrupted as follows: Part I ends with page 387 and Part II begins with 501, no text or tables being omitted thereby. Page 531 is left blank to make better openings for Table 2. The blank page preceding 621 is likewise not an omission. Pages 734 to 738 were formerly taken up with Tables 37 and 37A (see p. 503). 4 which have reference to examples for that year given in this work..... II. A collection of Forms for working Dead Reckoning and various Astronomical Sights, with notes explaining their application under all circumstances.... III. Explanation of certain Rules and Principles of Mathematics of use in the Solution 5 |