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Nathaniel Bowditch The Practical Navigator
Salem’s irascible little “arithmetic sailor” made seamanship a science and left all mariners in his debt
August 1960 | Volume 11, Issue 5
Such a voyage meant long watches when the entire crew was on deck. Time after time the anchor was let fly on the run to save them from a submerged reef or to assist them in clawing off a lee shore. On the ship struggled through unknown waters, past cannibal islands, relying on charts that were so incomplete and so filled with error as to be nearly useless. And all this in the face of the monsoon—the captain disdaining to wait for the fair wind the Good Lord himself had provided to bring simple and devout mariners safely to their destinations.
For the sailors the worst uncertainty of all, of course, was that of the ship’s position, known only to scrawny Nathaniel Bowditch, the supercargo, who could scarcely be trusted to stand a proper watch. Deeper and deeper the Astrea worked her way into the tortuous waters of the Indies. Time after time the ship was saved by the superb seamanship of Captain Prince and his crew. Nevertheless, as islands, channels, and capes kept appearing out of the mists exactly when and where Bowditch said they would, even the crew began to be impressed.
Bowditch was not content merely to navigate the ship himself. He knew that if his methods—and the book he was writing—were to be truly useful, they would have to be within the grasp of the most untutored seaman. Accordingly he undertook to teach every man in the Astrea to navigate, holding classes and drawing diagrams in chalk on the holystoned decks. The charts were explained to the men. He taught them how to use a sextant. Daily positions were worked out. He refined, sharpened, and clarified his explanations until finally every man aboard, from the cabin boy up, could establish the daily fix. Only then was Bowditch satisfied. He had already known that celestial navigation was trustworthy—he now knew that the involved astronomical concepts could be made simple enough for anyone to use, quickly and accurately.
In addition to navigating the vessel, teaching the crew, and standing his regular watch, he continued doggedly at work on the book. Besides the tables and the rest of the navigational material, he also began compiling a huge mass of related figures and information. He amended the ship’s charts. He developed and put down in precise and simple language methods for taking bearings, calculating distances, speeds, and other data vital to mariners working their vessels close to the land. He formulated exact terms and nomenclature for the construction, outfitting, and handling of ships. In short, he slowly began to compile a bible that would include everything men knew about ships and the sea.
The outward passage was finally completed. The dangerous complex of the Indies was again behind, the run up the China Sea was done, and the final “Land-ho!” rang from the masthead. The Philippines loomed dark and low on the horizon, precisely when Bowditch expected them to. Prince swiftly worked his way down the coast and a few days later quite non-chalantly let fly the anchor in the pale green waters of Manila Bay. The Astrea had completed the voyage in astounding time: six months, twenty-three days.
Her presence was unbelievable to the people of Manila. The ship claimed the impossible—a run through the Indies against the monsoon—but there was no disputing the facts as the evidence lay tranquilly swinging on her anchor in the harbor. Soon her crew, and Bowditch in particular, were local sensations—the pride of the handful of Americans living in the city. It was conceded that there was “more knowledge of navigation on board that ship than there ever was on all the vessels that ever floated in Manila Bay.” Captain Prince took pleasure in boasting that every man jack could take a lunar sight and work up a position “as well as Sir Isaac Newton himself, were he alive.””
“Captain Prince found a ready market for the goods in his floating warehouse, and soon trading was completed. The Astrea lay deep in the water, laden with sugar, pepper, indigo, and hides—commodities that would command high prices back in New England. The astonished Manilans were now due for another shock. The monsoon would shortly make its semiannual shift and would then blow steadily out of the southwest—the direction of the Astrea ’s homeward route. Any ordinary ship would have settled down to wait six months for the next shift and the necessary fair wind. But the Astrea was no ordinary ship. One fine morning the scholarly crew of mathematicians loosed the sails and weighed anchor. Disdaining the threat of the monsoon, they laid their course for Salem and home.
The return passage also was accomplished by celestial navigation and was made in record time, despite a bad leak that kept the men pumping for months on end. The vessel made her landfall on the Massachusetts coast in September, 1800, and sailed up the channel to an incredulous Salem approximately fourteen months after she had left.
If he had expected to be welcomed in triumph, Bowditch was disappointed. No triumph awaited him. Fortunately, however, he had returned from the sea with enough money to see his way clear to finishing the book, and once ashore, he kept at it. This was long before the days of mechanical calculators, and there were thousands upon thousands of complicated computations to be made for the tables. Since Bowditch was determined that his work could be trusted, he worked each set of figures three times.