slaves to Saint Helena was banned in 1792. In 1818, the governor freed children born of slaves on the island. The phased emancipation of over 800 resident slaves took place in 1827, some six years before the British parliament passed legislation to abolish slavery in the colonies. Between 1791 and 1833, Saint Helena became the site of a series of experiments in conservation, reforestation, and attempts to boost rainfall artificially. This environmental intervention was closely linked to the conceptualisation of the processes of environmental change and helped establish the roots of environmentalism. Crown colony (1834–1981) Under the provisions of the 1833 India Act, control of Saint Helena passed from the East India Company to the British Crown, and it became a crown colony. Subsequent administrative cost-cutting triggered a long-term population decline: those who could afford to do so tended to leave the island for better opportunities elsewhere. The latter half of the 19th century saw the advent of steamships not reliant on trade winds, as well as the diversion of Far East trade away from the traditional South Atlantic shipping lanes to a route via the Red Sea (which, prior to the building of the Suez Canal, involved a short overland section). In 1840, a British naval station established to suppress the Atlantic slave trade was based on the island, and between 1840 and 1849 over 15,000 freed slaves, known as "Liberated Africans", were landed there. In 1858, the French emperor Napoleon III purchased, in the name of the French government, Longwood House and the lands around it, the last residence of Napoleon I (who died there in 1821; his remains had been returned to France in 1840.) It is still French property, administered by a French representative and under the authority of the French Ministry of Foreign Affairs. A 2020 report states that the island's prosperity ended after 1869 when "the Suez Canal shifted trade routes north". A 2019 report explained that "ships no longer needed a stopping point on a longer journey to Europe". The number of ships calling at the island fell from 1,100 in 1855 to only 288 in 1889. On 11 April 1898 American Joshua Slocum, on his solo round-the-world voyage, arrived at Jamestown. He departed on 20 April 1898 for the final leg of his circumnavigation, having been extended hospitality by the governor, Sir R A Standale. He presented two lectures on his voyage