Thomas Sumner

American navigator

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June 17, 2026

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Thomas H. Sumner was an American sea captain who developed a significant method in marine navigation. His technique, known as Sumner's method, allows navigators to determine their position on Earth. This method involves assuming approximate latitudes or longitudes and then calculating corresponding positions based on observations of celestial bodies. The intersection of lines derived from these calculations pinpoints the observer's location. This astronomical determination, introduced in 1837, was a crucial advancement in making navigation more precise and systematic, complementing other techniques like dead reckoning.123

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…computations had been introduced by Thomas H. Sumner of the United States in 1837 and Marcq Saint-Hilaire of France in 1875. These astronomical determinations were supplemented by dead reckoning, which had been made more trustworthy by the continued development of compasses and logs.
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…computations had been introduced by Thomas H. Sumner of the United States in 1837 and Marcq Saint-Hilaire of France in 1875. These astronomical determinations were supplemented by dead reckoning, which had been made more trustworthy by the continued development of compasses and logs.
Read More