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Mr: Merrill is a frequent contributor to THE SUBMARINE REVIEW and is a published author of several books on the history of undersea technology. He is a retired engineer with lengthy experience at the New London lab of the Naval Undersea Warfare Center: He currently lives in Waterford, CT.

“Until Bowditch, ships found their way across ocean tracks with 110 exact calculation of their courses.”

In the more than 200 years since the first printing of Bowditch’s American Practical Navigator, the story of his life and his lasting contribution to marine navigation has appeared periodically in articles and books. The objective of this essay is to bring attention for perhaps a new audience to consider his admirable and broad accomplishments and fine character. What appears here is a brief reprise of some of his life’s highlights as noted over the years by various authors. The story of his life quickly reveals his determination to learn, know and grow in spite of his circumstances. His life was a full one and his navigation book soon to be known as Bowditch was perhaps the most important, but in no sense the only, contribution from his life’s work.

A 2002 Bicentennial Edition of this monumental navigation book, first published in 1802, included the latest advances in electronic navigation and digital charting technology and nonelectronic navigation. Starting in 1868, the US Hydrographic Office assumed publication. Over 75 editions and almost a million copies were printed. A 1940 comment about the book stated ” …it sells around 300 a month in peace times, and as much as 15,000 in wartimes.” Bowditch is carried on the bridge of every U. S. Navy ship.

Marine Navigation Pre-Bowditch (1800)

Compass, log, and lead provided most at sea indication of location in the years before 1800. Longitude without the assistance of the newly invented John Harrison chronometer time could have a 30-mile spread. By 1772, Harrison’s chronometer provided accuracy to five seconds after an 81-day voyage. Chronometers were scarce, in some instances even a watch was not available, and the chronometer did not come into general use until after the 1820s. 3 Astronomical observations served to support time correction and star sights to support latitude. At that time, some shipmasters did not hold celestial navigation in high regard for keeping a ship on course. “In those days it was not at all unusual for a New England vessel to wander toward her destination…”

Early Days

Reviewing Bowditch and his background and surroundings provides an awareness of living and growing up without ample means at (or near) poverty level during the hardships of the American Revolution and the following period. It is remarkable that in this environment, the pieces needed for his many future contributions fell into place for him. His small stature not withstanding, his unusual drive and intellect were essential factors in his eventual success.

Salem, Massachusetts and the surrounding communities with their strong connection to the sea and particularly the marine activity during and after the Revolution was the center of Bowditch’s world until his first sea voyage at twenty-two as clerk and navigator aboard HENRY, home ported in Salem. It took Bowditch around the Cape of Good Hope to Reunion Island off the southeast coast of Africa not far from Madagascar from January to December 1795. He was well prepared for the dual assignment years at sea.


Education usually has the connotation of being formal and carefully organized. The opportunities for Bowditch’s early learning could best be described as random. It turned out that he never ceased learning and made the time needed even when working ashore and in moments of opportunity on yearlong sea voyages. His mathematical skills, knowledge of science, languages, business matters and insurance, resulted in success in all his ventures. He has also been cited as the first American actuary.

Bowditch’s ancestors arrived in Salem almost 100 years before he was born in 1773. Going to sea provided vocations for many of the Bowditch male descendants. At the time of the arrival of Nathaniel (the fourth child with three more to follow), his parents Habakkuk and Mary (nee Ingersoll) frequently found themselves in impoverished circumstances. His father alternated working ashore and going to sea. On shore, he was engaged as a self-employed cooper during Nathaniel’s early years. When Nathaniel was three, the family moved a few miles from Salem to Danvers where his father worked at cooperage. It was in such grim pecuniary circumstances that Nathaniel spent his first ten years.

Beginning Education

When he was six, during the Revolution, the family returned from nearby Danvers to live again in Salem. For the next several years, he attended a local school with limited facilities. (Clark p84) Independently, a strong and Jong-time interest in mathematics attracted Nathaniel. There is documentation regarding Nathaniel’s mathematical skills from his earliest days. The family’s poverty brought even this very limited schooling to an end when he was ten. This was the last of his formal education and the beginning of his self-education, driven by his zeal that drove him to new studies all his life.

Continuing Education

At this point, he was apprenticed to Ropes and Hodges, a firm of Salem ship chandlers. This provided him with food, clothing and lodging at the home of Hodges. Surrounded every day by things nautical and in close proximity to ships, navigation (along with other wide-ranging interests) became important to him. Using the time from dawn to the start of work plus the hours after work, his knowledge grew. Salem was a small town, and encouragement came in the form of access to books. His ownership of books at this time came from the copies he made to create his own library.

At 13, he compiled a book on navigation. The next year, he started one on surveying. “The Practical Surveyor, Nathaniel Bowditch, County of Essex And State of Massachusetts, New England, March Seventh, 1787.” At the same age during his second year of apprenticeship, he read through four volumes of Chambers’ Cyclopedia that was the first English encyclopedia with an initial printing in 1728. Next, he discovered what turned out to be algebra, procured a book on the subject, and expanded his mathematical knowledge.

The Reverend William Bentley, one of Bowditch’s older Salem friends and supporter, a minister of exceptional scholarship and a linguist, secured the loan for Bowditch of Newton’s Principia. comprehensible to an advanced mathematician and written in Latin. In the next four years, Bowditch read it and found an error in it.

Another Salem minister, who befriended Bowditch, was the Reverend John Prince, who kept in his home (the Philosophical Society library) a scientific collection previously owned by a distinguished Irish scientist. He gave Bowditch access to one of the finest scientific libraries in America. In addition to reading and copying the mathematical papers from the Transactions of the Royal Society, Bowditch knew Shakespeare and the Bible intimately.

Having an interest in the works of French mathematicians and aware of ships leaving Salem for French ports convinced him to learn French. His technique for learning languages was to buy the dictionary of the language and a copy of the New Testament in that language and translate the book. Later, a French elocutionist residing at the time in Salem coached him in French for sixteen months. In exchange for his improved speaking proficiency, Bowditch taught the Parisian English.

As he approached his twenty-first year and the end of his apprenticeship with Ropes and Hedges, Bowditch’s avid pursuit of knowledge provided him with certainly the equivalency of a full college education. In particular, his deep understanding of mathematics, navigation, and astronomy plus his business knowledge from the ship chandlery made him an asset at sea. During this period on the practical side, he constructed and developed competency with the sextant, a primary tool aboard ship.

After Apprenticeship
Salem Region Survey

In 1794, the Massachusetts Legislature required each town to be accurately surveyed and its exact area be calculated. The town selected the Reverend John Prince, previously mentioned as one of Bowditch’s supporters, and John Gibaut, a sea captain to do the work. Prince offered Bowditch the position of calculator for the survey with a salary of $135. His acceptance of the assignment was pivotal as it led to the beginning of Bowditch’s nine years at sea. Captain Gibaut, impressed by Bowditch’s mathematical skills, offered him the opportunity to go on his next voyage as ship’s clerk.

At Sea: Five Voyages 1795-1804

Disagreement developed between the ship’s owner and Captain Gibaut. Captain Henry Prince of Salem was designated to the take the ship HENRY to sea. Bowditch was acceptable to Captain Prince and set sail on his first trip to sea on January 11, 1795. His shipboard duties included standing watches as second mate, navigation, and doing all the ship’s paper work for a ship engaged in trade with countries bordering the Indian Ocean. HENRY returned to Salem January 11, 1796. On this first trip, he invented a simpler method of taking lunar observations, which in those days before accurate chronometers was the most practical way of determining longitude. Chronometers were not affordable to ships sailing out of Salem. Voyages took Bowditch around the Cape of Good Hope to the Philippines and other locations in Southeast Asia and into the Mediterranean.

The second passage with Captain Prince was aboard the ASTREA, March 27, 1796 to May 22, 1797. The ASTREA gave Bowditch increased knowledge about navigation and the available tools for determining position. On this second trip, he started compiling notes of errors in The Practical Navigator written by former Royal Navy officer John Hamilton Moore and published in 1772. The Royal Navy placed Moore’s book in general use and by 1800 there were 13 editions in print. Bowditch also noted errors in navigation charts and other maritime books. A biographer of Bowditch opined regarding the notes “Unaware that he was doing so, he was slowly compiling a book on navigation.”

A ten-month voyage from August 15, 1798 to April 6, 1799 with Captain Prince aboard ASTREA, from Salem to the southeast coast of Spain in the Mediterranean, provided Bowditch with ample opportunity to enhance his knowledge and to be aware of existing errors in the available tools for navigation. By this time, Bowditch’s mathematical skills were well known in the Salem community and beyond. His recognition included being elected to the American Academy of Arts and Sciences in 1799, later becoming its president.

A local maritime publisher Edmund March Blunt, 1770-1862, was aware of Bowditch’s mathematical and navigational skills. Blunt, an entrepreneur from nearby Newburyport, Massachusetts, published charts, papers and books. Blunt was interested in creating an American corrected version of Moore’s navigation book. With assistance from Bowditch, a version of the Moore book with some corrections appeared in 1799.

ASTREA, with Bowditch in his navigator and supercargo role, was scheduled to depart Boston for Manila on July 22, 1799. Shortly before the ship’s departure, Blunt went aboard to solicit from Bowditch a complete revision of the Hamilton navigation book and verification of the thousands of figures in the tables. Bowditch accepted the task. The voyage of over one year returning to Massachusetts September 16, 1800, provided opportunity for Bowditch to continue his search for errors in certain navigation publications and tables (2,000 corrections). In Moore’s navigation book, he found 8,000 errors.

A table in the Moore navigation book contained an error regarding leap year and the sun’s declination. An 1838 book on the life and character of Bowditch points out the incorrect designation of the years 1792, 1796, 1800, and 1804 each being a leap year. The year 1800 was not a leap year. This error by Moore creates a difference of 23 miles in position in some instances and actually caused the loss of ships. “This error was the cause of losing two vessels to the northward of Turk’s Island and bringing others in serious difficulties.

It is often cited that on this trip, Bowditch taught every man of the crew of twelve, including the ship’s cook to take and calculate lunar observations and to plot the correct position of the ship.

November 21, 1802, Bowditch sailed out of nearby Beverly, Massachusetts to the Indian Ocean on the newly constructed PUTNAM. Bowditch and three other men from Salem jointly owned the ship. He was the master, navigator and in charge of the business transactions of the voyage. This last voyage was a successful financial business venture and upon returning to Beverly from Sumatra December 25, 1803, he was able to retire from the sea. Two years after his return, PUTNAM was on a voyage to the Indian Ocean and natives overtook it and massacred entire crew.

Prior to sailing, Edmond March Blunt, Bowditch’s associate gave him a copy of Celestial Mechanics by the Pierre Simon Laplace (1749-1827) the French mathematician, astronomer, and physicist. Laplace was best known for investigations into the stability of the sun. Blunt suggested that Bowditch translate it into English. He began the translation on his last voyage and then later devoted about thirty years to it after he came ashore, Bowditch created a multivolume 4,000 page version that was printed and internationally acclaimed.

The New American Practical Navigator: “Bowditch” First Edition 1802

Six hundred pages of remarkably accurate printing, in the original manuscript by Bowditch, included thousands of corrections to the Moore tables and other well-known maritime tables. “The New American Practical Navigator was not just another navigation book. It was a tool- as important as sextant or compass.”

Regarding the publication of this first edition, followed with approximately 70 editions by 1955, the above-mentioned Edmund March Blunt brought more than encouragement to Bowditch. Starting his bookstore and publishing in 1793, Blunt’s interest and experience in manuscript acquisition, including maritime-related material, benefited acceptance of the new book. Further, Blunt was broadly known in maritime circles including England.

The title page describes the book as an “epitome of navigation: containing all the tables necessary to be used with the Nautical Almanac, in determining the latitude, and the longitude by 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… by Nathaniel Bowditch, Fellow of the American Academy of Arts and Sciences.” Chapters covered a wide range of material on winds, currents, the obligations of an owner, the duties of a master, a dictionary of sea terms, an explanation of all-possible maneuvers of square-riggers at sea and the appropriate commands for their accomplishment. There are even sections on marine insurance, bills of lading, and bills of exchange. Mathematics is not only included, it is taught including decimals, geometry, algebra, logarithms, trigonometry and calculus of navigation. The table for relating the distance of visibility of objects at sea is still in use.

The Salem East India Marine Society authenticated the work of Bowditch, and Blunt provided seven separate printings of the first edition, each for a different bookseller on the New England Coast. This edition was so large enough that another was not needed for five years. One hundred years later, a 1903 remembrance in a Naval Institute Proceedings article about Bowditch noted that within several years of initial publication seven thousand copies were sold in the United States. Eventually it became extensively used in the British and French navies.

Matthew Fontaine Maury (1806-1873)

Maury and Bowditch shared self-education and are sometimes compared in their contributions to those who follow the sea. Maury, an outstanding United States Navy officer, was a scientist, chart maker and oceanographer and after his initial nine years at sea he wrote “A New Theoretical and Practical Treatise on Navigation” in 1835. His purpose was to provide a more thorough textbook suited to the needs of the US Navy midshipmen. It took the place of Practical Navigator for junior officers in the Navy and by 1837 was on every Navy ship. When the Naval Academy was established at Annapolis in 1845, it was used for several years as the basis for instruction to midshipmen in navigation.

At the time when Maury’s book was in final preparation, Bowditch sent him a letter commending his book. In addition to providing satisfaction to Maury, the letter helped the book’s acceptance. By this time, Bowditch was well known nationally and internationally beyond the authorship of his navigation book. Maury asserted that a more theoretical navigation book than Bowditch was needed. “The ground designed to be covered by this work is unoccupied this is not designed to conflict with Dr. Bowditch’s, for by a mere reference to the pages of his, the necessity of a work, more theoretical in its nature becomes obvious” wrote Maury to his publisher of the navigation book.

Bowditch to Maury: “A work of the kind you are preparing for the press, containing the demonstrations of the formulas of Nautical Astronomy, would be very useful to those who have a taste for the subject and would like to examine the demonstration of the rules.”

After the Voyages

Bowditch’s active participation and contributions in business (insurance), science, and other professional activities brought him to national and international fame in the years after his sea duty. In 1803 he and other men from Salem, organized with his mathematical skills the Essex Fire and Marine Insurance Company, serving as its president for twenty years and actuary. He was the first American actuary. The Company was successful and in addition, Bowditch managed estates and trusts. In 1823, he became actuary of the Massachusetts Hospital Life Insurance Company and moved to Boston from Salem.

Prior to his move, he wrote 23 papers on astronomy and mathematics. His ability in mathematics provided him with teaching opportunities he did not accept. They included: a Harvard mathematics and physics chair, a mathematics chair at the University of Virginia offered by President Thomas Jefferson, and a mathematics chair at West Point offered by Secretary of War John C. Calhoun.

His professional affiliations included the Edinburgh Royal Society, Royal Society of London, Royal Irish Academy, Royal Astronomical Society of London, Royal Academy of Palermo, British Association, Royal Academy of Berlin, American Philosophical Society, Connecticut Academy of Arts and Sciences, and the Literary and Philosophical Society of New York.

From Harvard, he was awarded a Doctor of Law Degree and from 1810-1826 he was on the Board of Overseers. “During 1826-27 he was the leader of a small group of men who saved the school from financial disaster by forcing necessary economies on the college’s president.

Regarding the above-mentioned English translation of Laplace’s Celestial Mechanics, Bowditch’s corrected version removed errors, supplied omitted proofs and included attribution of other scientists. The annotated edition, nearly doubled the size of the original and constituting a major critical work, was well received by European scientists and brought Bowditch to further international fame. Publication at his own expense, Bowditch spent one third of his worth to have the four volumes brought to fruition between 1829 and 1839, the year following his death.

Comments about Bowditch
A Mathematician

Bowditch was considered as primarily a meticulous and exhaustive critic having exceptional mathematical skills. He found his most receptive audience in Europe with few in America who could follow his mathematical work. He died on March 17, 1838.

The Boston Athenaeum -1838

“His fame is of the most durable kind, resting on the union of the highest genius with the most practical talents, and the application of both to the good of his fellow man.”

The Salem Marine Society Eulogy

“…but as long as ships shall sail the needle point to the north, and the stars go through their wonted courses in the heavens the name of Dr. Bowditch will be revered as of one who has helped his fellowmen in time of need, who was and is a guide to them over the pathless oceans, and one who forwarded the great interests of mankind.”

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