Saturday, October 23, 2010

Book Of The Month - 'The American Practical Navigator (Bowditch)'

The Book of the Month for October 2010 comes under the heading of Books Every Man Should Own.

In 1802 a Massachusetts surveyor, sailor, ship owner, amateur mathematician and scientist and overall practical genius published a work on navigation that was so eminently practical, accurate and easy to use (so damned Yankee-like, as some would say) that it revolutionized maritime navigation.

That man, Nathaniel Bowditch, and his work, 'The New American Practical Navigator' brought maritime navigation to the masses, and it is this work that set the foundation for the 19th Century explosion of American maritime trade.  The impact of Bowditch's work can be said to have had the same impact on the US maritime industry as the development of the marine chronometer had on the British maritime industry.

Bowditch's original 1802 edition

By the early 1800s the Industrial Revolution was hitting its stride and raw materials and finished goods were pouring out of the expanding American interior.  Demand was exploding not just between American cities and states, but the rapidly expanding textile industry in Europe was driving an almost insatiable demand for American raw materials like cotton.  Suddenly America discovered she had worldwide markets, and the fledgling American maritime industry was growing apace to make sure that American goods were carried on American ships.

Using Bowditch's work, a literate and sharp young seafarer could teach himself all he needed to know to safely navigate hs vessel across the vast emptiness of the world's oceans, or down the treacherous coasts of the Americas.

Bowditch's genius came into play in two specific areas.  First was the accuracy of his navigation tables.  Working with an edition of a popular British navigation book titled 'The Practical Navigator', Bowditch noted a number of errors in the navigation tables.  Most were minor - transposed numbers out at the 3rd or 4th decimal - but some were critical, like a misplaced leap year in a solar declination table.  Bowditch applied his mathematical and analytical skills towards cleaning up these tables.  When he was finished seafarers had, for the first time, a complete and accurate set of navigation tables.

Second was Bowditch's ability to distill maritime navigation concepts and techniques down into easily understood and practiced methods.  Bowditch realized that most navigators and ships' captains of his day had only a basic education, and newfangled navigational instruments like the marine chronometer were out of the reach of most.  Bowditch focused on 'practical' navigation, emphasizing dead reckoning techniques.  While celestial navigation was included in his work, Bowditch understood that most navigators would use it only for latitude determination (again, the no marine chronometer thing), and they still relied on dead reckoning to estimate their longitude.  Bowditch incorporated improved, easily understood dead reckoning methods into his work that greatly improved the accuracy and safety of open water navigation.

(It should be noted that Bowditch did spend a good bit of time discussing the Lunar Distance method of longitude determination in his book.  The Lunar Distance method is quite accurate, but doing it successfully takes a good bit of practice and it is difficult to execute while standing on the deck of a ship at sea.  However, the Lunar Distance method did not require the use of one of those newfangled, expensive and temperamental marine chronometers.  My suspicion is that most navigators didn't even try to use the Lunar Distance method.  They just relied on an accurate latitude determination using star or solar shots to develop a line of position, then used their well honed dead reckoning skills to guesstimate longitude.  This was 'close enough' until they made landfall and could pick up known landmarks and adjust their position.)

In the beginning Bowditch was out to just correct the errors he noted in 'The Practical Navigator'.  The book's American publisher asked him to contribute any other improvements or changes he felt were necessary.  Over time Bowditch contributed so many updates, improved techniques and additional chapters that the publisher felt that the work had become a full reflection of Bowditch's efforts.  Therefore, the 1802 edition was credited fully to Nathaniel Bowditch and the title changed to 'The New American Practical Navigator'.

Nathaniel Bowditch continued to update the work until his death in 1839.  Over those 37 years his work became the navigation reference standard for the US maritime industry.  'The New American Practical Navigator' could be found aboard almost every US vessel plying the world's oceans.  It was purchased and used by ships' captains and officers, along with schools, training academies, universities and, most notably, by the US Navy.  It was considered such an important text that in 1868 the US Navy Hydrographic Office purchased the copyright and took over updating and publishing the book.

OK, so we know how Bowditch's work got here.  What about the why?  Why does every Man need a copy?  Simple.  It is stuffed full of so much useful and necessary manly knowledge that every guy needs a copy.

Need to know how to adjust your binnacle compass?
Need to know how to degauss your ship?
Need to know how to adjust for perpendicularity error on your sextant?
Need to know how to solve right spherical triangles using Napier's Rules of Circular Parts?
Need to know how to construct a great circle track on a Mercator projection?
Need to know how to route your fleet to avoid cyclones in the North Pacific?
Need to know how to plot a line of position using a Loran-C signal?

The answers to all of these and many, many more of life's vexing manly issues can be found in 'The American Practical Navigator'!

You can buy a copy of 'The American Practical Navigator' directly from the US Government Printing Office or from for a relative pittance.  It is a manly book, with well over 800 pages stuffed full of manly knowledge.  Or, you can be a cheapskate and download a copy free from the National Geospatial-Intelligence Agency website.

Either way, if you are a Man get a copy!


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