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Fellow of the Royal Societies of London, Edinburgh, and Dublin; of the Astronomical Society in London; of the
American Philosophical Society, held at Philadelphia; of the American Academy of Arts and Sciences;
of the Connecticut Academy of Arts and Sciences; of the Literary and Philosophical Society

of New York; Corresponding Member of the Royal Societies of Berlin, Palermo, &c.

Revised in 1880, under the direction of the Bureau of Navigation,

Navy Department.
Revised in 1903, under the direction of the Bureau of Equipment,

Navy Department.

WASHINGTON:
GOVERNMENT PRINTING OFFICE.

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BUREAU OF NAVIGATION,

Navy Department, January 1, 1881. In accordance with the purpose contemplated in the purchase of the copyright of the New AMERICAN PRACTICAL NAVIGATOR, a thorough and complete revision has been made by Commander P. H. Cooper, U. S. Navy, acting under the direction of the Bureau. The revision consists principally in the substitution of the more concise and convenient methods of the present day for the obsolete methods of the past, and a complete rearrangement under proper chapters and paragraphs for ready reference, keeping in view, however, the character of the work as a Practical Navigator.

The revision having been completed, it was submitted to Capt. Ralph Chandler, U. S. Navy, for a final review, and having received a satisfactory report from that officer it has been accepted by the Bureau and will hereafter be substituted for the former editions of the work.

WILLIAM D. WHITING,

Chief of Bureau.

BUREAU OF EQUIPMENT,

Navy Department, March 18, 1903. A revision of Bowditch's AMERICAN PRACTICAL NAVIGATOR having become necessary, the work has been completed by Lieut. G. W. Logan, U. S. Navy, under the supervision of the Hydrographer to the Bureau of Equipment. The revision was approved by a Board consisting of Capt. Colby M. Chester, U. S. Navy, Commander C. J. Badger, U. S. Navy, and Lieut. Commander C. C. Rogers, U. S. Navy. It is directed that this revised edition be substituted for all former editions.

R. B. BRADFORD,

Chief of Bureau. 2

2649

PREFACE.

The copyright of the New AMERICAN PRACTICAL NAVIGATOR, by the late Dr. Bowditch, became the property of the United States Government under the provision of an act of Congress to establish a Hydrographic Office in the Navy Department, approved June 21, 1866.

Under the direction of the Bureau of Navigation, at that time charged with such publications, the work was revised in 1880 by Commander P. H. Cooper, U. S. Navy, certain chapters being contributed by Lieuts. Richard Wainwright and Charles H. Judd, U. S. Navy, and the whole being reviewed by Capt. Ralph Chandler, U. S. Navy. The object of this revision was to improve the general arrangement, and to introduce the more convenient and precise methods of navigation that had come into practice since the book was originally written.

The progress that has been made in the science of navigation since 1880 has rendered necessary a second extensive revision, to take cognizance of the changes of methods and instruments that have accompanied the general introduction of high-speed vessels built of iron and steel. This work has been carried out, under the direction of the Bureau of Equipment, by Lieut. G. W. Logan, U. S. Navy, who was aided in the collection of data and preparation for publication by Lieut. T. A. Kearney, U. S. Navy; the chapters on Winds and Cyclonic Storms were contributed by Mr. James Page, nautical expert, Hydrographic Office.

There has been an extensive rewriting of the text, with the object of amplifying those matters that are of the greatest importance in the modern practice of navigation, and of omitting or condensing those of lesser importance; and the revision of the tables has proceeded along similar lines. This has involved, among other things, a much wider treatment of the subject of the compass; an extension of the traverse table for degrees to distances up to 600 miles; an improved table for reducing circummeridian altitudes; the combination of the tables of maritime positions and tidal data; the omission of certain special methods for finding position by two observations; the addition of a series of annotated forms for the working of all sights, and the introduction of a number of new tables of use to the navigator.

The explanation of the method of lunar distances, with its accompanying tables, has been retained, in order to be available for use when required; but since this observation is so rarely employed in modern navigation, everything pertaining thereto has been incorporated in an appendix, that it may be distinct from matter of every-day use to the navigator.

For convenience in use the work has been divided into two parts, of which the first comprises the text and its appendices, and the second the tables.

W. H. H. SOUTHERLAND,

Commander, U. S. Navy, Hydrographer. HYDROGRAPHIC OFFICE, BUREAU OF EQUIPMENT, NAVY DEPARTMENT,

Washington, D. C., March 19, 1903.

3

NOTE.

This edition is a reprint of the revised edition, 1903, with no change made in the text or tables of that edition except the correction of such errors as have been discovered in it to the present date.

HENRY H. BARROLL, Commander, U. S. Navy (Retired), Acting Ilydrographer. HYDROGRAPHIC OFFICE, BUREAU OF EQUIPMENT, NAVY DEPARTMENT,

Washington, D. C., August 16, 1906. 4

PART I.

TEXT AND APPENDICES.

5

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