Robert FitzRoy had long been interested in meteorology and, in particular, convinced of the barometer's value. In 1829, during his first voyage in command, his ship had nearly capsized in a squall off Uruguay. There had been barometers on board and low pressure indicated, but anchors, topmasts, jib-boom and two men had been lost. He never again ignored the barometer's warnings. Indeed, he interpreted the instrument's readings so skilfully during his second surveying expedition that he weathered the severest gales without the loss of anyone on board or even damage to his ship. The voyage lasted almost five years (December 1831–October 1836) and proved a watershed in FitzRoy's life. It was a personal triumph which enhanced his reputation as a skilled and meticulous surveyor. He was thanked in Parliament, praised by the Hydrographer of the Navy and awarded the gold medal of the Royal Geographical Society. The ship was HMS Beagle, and the expedition was the famous circumnavigation of the globe with Charles Darwin on board.

FitzRoy was born on 5 July 1805 and educated first at Rottingdean School near Brighton and later Harrow School. He entered the Royal Naval College at Portsmouth in February 1818 and took only twenty months to complete the course of study, which normally took three years. He went to sea when he was 14, a volunteer aboard HMS Owen Glendower, and later served aboard HMS Superb and HMS Hind. He was promoted to the rank of Lieutenant on 7 September 1824 and subsequently served aboard HMS Thetis and HMS Ganges. He took command of HMS Beagle on 13 November 1828 and advanced to the rank of Captain on 3 December 1834.