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in London, and has a derided preference to any ertant.
tile information for Merchants and Shipmasters. [In this work all recent commercial regula
tions are introduced, and the most experienced will find something new.] THE EXPEDITIOUS MEASURER, containing a set of tables, which show at one view the solid contents of all kinds of packages and casks, according to their several lengths, breadtbs, and depths ; also rules for determining the contents of all sorts of casks, in wine and beer measure. A stereotype edition. NAUTICAL ALMANACS, from the year 1811 to 1828, both inclusive—to be continued annually. Es
planation stereotyped, and English copy corrected.
( 1826, Over Fifty errors
1828, Over Twenty errors
proved by actual Surveys of the Chesapeake Bay, by order of the Navy Department,
Coast of Guayana --of the Coast of Brazil.-of the Island of Bermudas, with Sailing Directions.-of Long-Island Sound, improved to 1825.--of the Coast of Labrador.--of Newfoundland of the Coast of Brazil, from Maranbam to the river La
Plate, &c. &c. the sailing Directions for which are in'Blunt's American Coast Pilot. PLAN of New-London ílarbour, surveyed by CHARLES MORRIS, Esq. of the United States Navy,
by order of Commodore RODGERS, and to him respecifully dedicated. SOUTHERN DISTRICT OF NEW-YORK, ss.
BE IT REMEMBERED, That on the twenty-second day of June, A. D. 1824, in the 'fiftieth year of the Independence of the United States of America. Edmund M. Blunt, of the said district, hath deposited in this office the title of a book, the right whereof he claims as proprietor, in the words following, 10 wit:
“ The New American Practical Navigator : being an Epitome of Navigation : containing all the Ta. "bles necessary to be used with the Nautical Almanac, in determining the Latitude, and the Longitude Ilsy Lunar Observations; and keeping a complete Reckoning at Sea ; illustrated by proper Rules " and Examples: the whole exemplified in a Journal, kept from Boston to Madeira, in which all the & rules of Navigation are introduced. Also, the Demonstration of the usual Rules of Trigonometry; “ Problems in Mensurution, Surveying, and Gauging; Dictionary of Sea-Terms; and the manner of per“ forming the most useful Evolutions at Sea. With an Appendix, containing Metbors of calculating Eclip"ses of the Sun and Moon and Occultations of the Fixed Stars ; Rules for finding the Longitude of a “ place hy "Observations or Eclipses or Occultations : and a new method for finding the latitude by «iwo altitudes. By Natbaniel Bowditch, LL. D. Fellow of the Royal Societies of London, Edipburgh, & and Dublin; of the American Philosophical Society, held at Philadelphia ; of the American Academy " of Arts and Sciences; of the Connecticut Academy ot Arts and Sciences; of the Literary and Philo“ sophical Society of New York, &c. Sixth stereotype edition."
In conformity to the act of congress of the United States, entitled “Ar Act for the encouragement of learning, by securing tbe copies of Maps, Charts, and Books, to the Authors and Proprietors of such copies, during the time therein mentioned.” And also to an act, entitled "an act supplementary 10 an act, entitled an act for the encouragement of learning, by securing the copies of Maps, Charts. and Books, to the authors and proprietors of such copies, during the times thered mentioned, and extend. ing the benefits there of to die arts of designing, engraving, and etching historical and other privis."
ry mercancial regular
Of the Committee, appointed by the East INDIA MARINE Society of Sulim, at their meeting on the 6th of May, 1801, to erumine a work called " The New American Practical Navigator, by Nathaniel Bouditch, F. A. A."
* the solid und depths ; 4 stereotype
annels, im. Department, act of CooLLIOT, Esq. 1, Secretary th Carolina
AFTER a full examination of the system of Navigation presented to the society by one of its members (Mr. Nathaniel Bowditch) they find, that he has corrected many thousand errors existing in the best European works of the kind; especially those in the Tables for determining the latitude by two altitudes, in those of difference of latitude and departure, of the sun's right ascension, of amplitudes, and many others necessary to the Navigator. Mr. Bowditch has likewise, in many instances, greatly improved the old methods of calculation, and added new ones of his own. That of clearing the apparent distance of the moon, and sun or stars, from the effect of parallax and refraction, is peculiarly adapted to the use of seamen in general, and is much facilitated (as all other methods are) in the present work, by the introduction of a proportional table into that of the correction of the moon's altitude. His Table nineteenth, (the twentieth of the present edition) of corrections to be applied in the lunar calculations, has the merit of being the only accurate one the Committee are acquainted with. He has much improved the table of latitudes and longitudes of places, and has added those of a number on the American coast, hitherto very inaccurately ascertained.
W ORTAY, also several
e, &c. with Y; published ailing direcARI, U.S. 1 that nine irvey, since dmits not a ost correct
This work, therefore, is, in the opinion of the Committee, highly deserving of the approbation and encouragement of the society, not only as being the most correct and ample now extant, but as being a genuine American production ; and as such they hesitate not to recommend it in the attention of Navigators, and to the public at large.
ude 470 N. ke's Bank,
he authori. cks extend aan an extant, ? Harbours
BENJAMIN HODGES, President.
the Chart edas, with tol Labra
river La 251 Pilot. ates Narr,
A TRUE COPY. MOSES TOWNSEND, Secry.
Salem, May 19, 1801.
stieth rear the depasite following,
J! the Ta. Longitude HET Rules
all the cometry; er of perng Ecliptude of a titude by Nirburgb, Academy rd Plusio
75ement prietors mentary arts and
IN the preface to the first edition of this work, it was observed, that the object of the publication was to collect into one volume all the rules, examples and tables necessary for forming a complete system of practical navigation. To do this, those authors were consulted whose writings afforded the best materials for the purpose,* and such additions and improvements were introduced as were suggested by a close attention to the subject; and the accuracy of the tables accompanying the work was ensured by actually going through all the calculations necessary to a complete examination of them, making the last figure exact to the nearest unit. In performing this, above eight thousand errors were discovered and corrected in Moore's Practical Navigator, and above two thousand in the second edition of Maskelyne's Requisite Tables. Almost all the errors in Maskelyne's collection were in the last decimal place, and in most cases would but little affect the result of any nautical calculation ; but when it is considered that most of those tables are useful in other calculations, where great accuracy is required, it will not be deemed an unnecessary improvement to have corrected so great a number of small errors.
Several articles were added in the second edition, particularly the description and use of the circular instrument of reflection, methods of surveying harbours, new tables, &c. In the third and subsequent editions, several improvements have been made, particularly in the method of correcting the dead reckoning, and in the articles of surveying. An Appendix is given, containing methods of projecting and calculating eclipses of the moon and sun, and occultations of the fixed stars or planets by the moon; rules for deducing the longitude of a place from observations of eclipses of the sun or occultations; a new and short method of calculating the altitude and longi tude of the nonagesimal degree of the ecliptic ; solutions of several useful problems of Nautical Astronomy, and an improvement of Napier's rules for the solution of spheric triangles. Several new tables were added. The table of latitudes and longitudes is much increased and corrected.
Also an entirely new article is given in this edition on the method of finding the latitudes by two altitudes of the same, or of different objects: the solutions being direct and simple, embracing all the cases of the problem: a point which has not been attended to in some works of celebrity. This is an important addition to the present work, and it is recommended to the consideration of navigators.
The tables published separately in the Appendix of the first edition are introduced into the body of this work, and are extended so as to render the use of them more simple. The short and easy method of working a lunar observation, published in that Appendix, which has one great advantage over all other approximate methods, in the manner of applying the correc tions (all them being additive) is here explained and illustrated by several examples.1 Two other methods of correcting the apparent distance are given; one being that invented by the author of this work in the year 1795 ;
The works chiefly consulted were those published by Maskelyne, Roberston, Patoun, Rios, de and a treatise on "Seamanship,” published at London in 1795. In this new edition, the work of the Cbevalier de Borda, entitled " Description et Usage du Cercle de Reflection, " &c. bas also been used.
In the third edition of that work the errors of the table of proportional logarithms are cor. recird.
This method was communicated to Mr. De Lambre, who published an account of it in the * Connoissance des temps pour l'annee, 1808."
the other an improvement of Witchell's method, in which, without altering materially the calculation, the number of cases is considerably reduced.
To promote the accuracy of the successive editions of this work, all the tables (which admit of it) have been stereotyped, namely, Tables I. II. III, V. VII. IX. X. XI. XII. XIII. XIV. XV. XVI. XVII, XVIII. XIX. XX. XXI. XXII. XXIII. XXIV. XXV. XXVI. XXVII. XXVIII. XXIX. XXX. XXXI. XXXII. XXXIII. XXXIV. XXXV. XXXVI. XXXVIII. XXXIX. XL. XLI. XLII. XLIII. XLIV. and XLV. Since the publication of the first stereotype edition, these Tables have been carefully examined by the author, and the few mistakes which were discovered, have been corrected in the plates.
Any person who wishes to examine the tables, may do it by the methods used for that purpose, which will here be explained with some additional remarks.
TABLES I. and II. were calculated by the natural sines taken from the fourth edition of Sherwin's logarithms, which were previously examined, by differences; when the proof-sheets of the first edition were examined, the numbers were again calculated by the natural sines in the second edition of Hutton's logarithms; and if any difference was found, the numbers were calculated a third time by Taylor's logarithms.
TABLE III. contains the meridional parts for every degree and minute of the quadrant, calculated by the following rule, viz.
M=TX 0.0007915704468. in which T is the log-tangent less radius of half the latitude increased by 45° taken to seven places of figures, reckoned as integers, and M is the meridional parts of that latitude in miles.
TABLE IV. contains the declination of the sun, which was compared with the Nautical Almanacs for the years 1824, 1825, 1826, and 1827, and marked to the nearest minute.
TABLE IV. A. The Equation of Time, for the years 1824, 1825, 1826, and 1827.
Table V. contains the correction of the sun's declination, as published by Dr. Maskelyne. The correction taken from this table will rarely differ more than 16 or 17 seconds from the truth.
TABLE VI. contains the mean of the sun's right ascension, taken from the Nautical Almanacs for the years 1824, 1825, 1826, and 1827.
TABLE VI. A. contains the correction for the daily variation of the Equation of Time.
Table VII. contains the amplitudes of the sun for various latitudes and declinations calculated by Taylor's logarithms by this rule : Log. sec. lat. +Log. sine declination—10.0000000=Log. sine amplitude.
TABLE VIII. contains the right ascensions and declinations of 76 stars of the first and second magnitudes, with their annual variations, adapted to the beginning of the year 1820. This table was formed from that published by the Astronomer Royal at Greenwich (Mr. Pond) in the Nautical Almanac for 1823, with the addition of a number of stars from the Catalogue of Baron Von Zach.
TABLE IX. contains the time of the sun's rising and setting, calculated by Taylor's logarithms by this rule : Log. cos. hour=Log. tang. declin. + Log. tang. latitude-10.0000000,
Table X. contains the distances at which any object is visible at sea, calculated by the rule given in § 195 of Vince's Astronomy, in which the terrestrial refraction was noticed : this circumstance was neglected by Robertson, Moore, and others, and of course their tables are erroneous. The rule given by Mr. Vince, expressed in logarithms, is this :
0.12155 +Half log. of height in feet=Log. of dist. in statute miles. In reducing the rule to logarithms, the radius of the earth was called 20911790 feet, which agrees nearly with the mean value given in De La Lande’s Astronomy.
TABLE XI. is a common table of proportional parts, the construction of which does not need any explanation.