A New Look at Nathaniel Bowditch, Nineteenth-Century America's Numbers Man f there is one reason that Nathaniel Bowditch 's New American Practical Navigator, first published in 1802, became the standard American maritime manual, it was the accuracy of its navigational tables. Yes, as a replacement for the old standby, Englishman John Hamilton Moore's New Practical Navigator, Bowditch's work held patriotic appeal. And it was true enough that Bowditch 's Navigator was clearer and better organized than Moore's, even if most of the text was essentially the same. But it was the numbers that sold American mariners on Bowditch. The unprecedentedly reliable tables, keyed to the mathematically regular movements of heavenly bodies, allowed mariners to establish their position at sea with certainty. Bowditch didn't create these numbers, of course, as they were based on the universals of mathematics and astronomy, as were Moore's. But, being a numbers man, Bowditch reworked tens of thousands of calculations and discovered no fewer than 8,000 errors in Moore's published tables. Despite the fact that it had been the most popular navigational text since it was first published in 1772, it was no secret that Moore's numbers couldn't be trusted; in 1791, Thomas Jefferson wrote that "the later edns. are so incorrect as to be worth nothing." 1 In welcome contrast, you could stake your life on the accuracy of Bowditch's numbers. Many mariners did, and theyand their cargoes-made it to their destinations safely. To Bowditch, the precision of numbers and the regularity and predictability of the solar system offered more than reliable navigational data. They inspired a vision that extended beyond the sea and the sky to dry land. In fact, if we know Bowditch only as the author of the Navigator-or even as an astronomer and mathematician of some note-we are missing out on what made the man tick, and his even longer lasting and broader legacy. It was a temperamental commitment to numerical precision that would guide all his endeavors and launch Bowditch on h is nautical publication project. The Navigator grew out of his mission to correct Moore's tables of numbers. Think fo r a moment about what was involved. These
by Tamara Plakins Thornton
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Second edition copy ofThe New American Practical Navigator, by Nathaniel Bowditch, printed by Edmund M. Blunt, May 1807 This copy is available for purchase at the Arader Gallery in New York. www.aradernyc.com. numbers had first been generated by people termed "computers," toiling away with pen and paper. Sophisticated mathematical knowledge was not required; patience was. "Nothing can exceed the tediousness and ennui of the life the assistant leads in this place," wrote a computer at England's Greenwich Observatory in 1809. "He spends days, weeks, and months in the same long wearisome computations." 2 It seemed impossible that such endless drudgery could produce perfectly accurate res ults, and in fact it could not. "I wish to God these calculations had been executed by steam," exclaimed English mathematician Charles Babbage, mindful of how inhumane the labor was and how many lives and how much treasure rode on the reliability of nautical tables.3 By 1833, he had designed the first mechanical computer for precisely that task. But for Bowditch, such calculations were anything but "wearisome." They had long been a source of pleasure to him and wonderment to others, giving him a reputation as a mathematical whiz. In his youth, people believed that the sign of mathematical brilliance was not abstract theorizing, but doing complex arithmetic problems in one's head. Bowditch excelled at these computational parlor tricks. When he was a ship's clerk, mate, and supercargo in the 1790s, his captain used to brag that Nathaniel was "the greatest calculator in
America,"4 even placing bets on his success in mathematical challenges. It must have been galling, then, when a new entrant in the business of navigation manuals, Scotsman Andrew Mackay, questioned the accuracy of Bowditch's numbers. The American's Navigator "pretended to be very correct," wrote Mackay in the preface to h is Complete Navigator, published in London two years after his Yankee rival's, bur in fact it was filled with "many errors and contradictions." After pointing out a few such mistakes, he concluded that it would be "a tedious task to enumerate the errors contained in the above-mentioned book." 5 Mackay's Philadelphia publisher added his own taunt, noting that "pretensions to accuracy are, indeed, more numerous than real attentions to that subject."6 In a suddenly competitive market for navigation manuals-Bowditch (1802), Mackay (1804), and Englishman J. W. Norie (1805) now contended with Moorethe Scotsman's critique posed a real threat. Initially, American booksellers carried all four books. Who would win out? Who was the real authority? Surely Mackay was a man whose word carried weight. Though not a un iversity graduate, he had received two honorary doctorates, been elected to the Royal Society of Edinburgh, and taught mathematics, astronomy, and navigation in Aberdeen and London. Who was this Bowditch? A self-taught supercargo w ith SEA HISTORY 160, AUTUMN 2017