A New Look at Nathaniel Bowditch, Nineteenth-Century America's Numbers Man

摘要

If 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 they-and their cargoes-made it to their destinations safely.