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How accurate were the longitude measurements made during HMS Beagle’s second voyage?

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HMS Beagle on the Strait of Magellan, South America, originally published in an 1890 edition of Charles Darwin's Journal of Researches into the Geology and Natural History of the Various Countries Visited by H.M.S. Beagle. — Beagle HMS *Beagle* on the Strait of Magellan, South America, originally published in an 1890 edition of Charles Darwin's *Journal of Researches into the Geology and Natural History of the Various Countries Visited by H.M.S. Beagle*.

During HMS Beagle's second voyage (1831-1836), longitude measurements were remarkably accurate, achieving a complete circle of measurements within only 33 seconds of error. This accuracy was made possible by the development and use of marine chronometers, which allowed for reliable timekeeping at sea. Before the advent of accurate marine chronometers, determining longitude was a significant challenge for navigators. The Beagle carried 22 chronometers for this purpose, contributing to the successful completion of this navigational feat.12