population. The islands were occupied by a garrison of British Marines, and a civilian population gradually grew. stopped there on 25 March 1824 and reported that it had a population of twenty-two men and three women. The barque South Australia stayed there on 18–20 February 1836 when a certain Glass was Governor, as reported in a chapter on the island by W. H. Leigh. Whalers set up bases on the islands for operations in the Southern Atlantic. However, the opening of the Suez Canal in 1869, together with the gradual transition from sailing ships to coal-fired steam ships, increased the isolation of the islands, which were no longer needed as a stopping port for lengthy sail voyages, or for shelter for journeys from Europe to East Asia. A parson arrived in February 1851, the Bishop of Cape Town visited in March 1856 and the island was included within the diocese of Cape Town. In 1836 the schooner Emily ran aground with the Dutch fisherman Pieter Groen from Katwijk. He stayed, married there, changed his name to Peter Green and in 1865 became spokesman/governor of the community. In 1856 there were already 97 people living there. In 1867, Prince Alfred, Duke of Edinburgh and second son of Queen Victoria, visited the islands. The only settlement, Edinburgh of the Seven Seas, was named in honour of his visit. On 15 October 1873, the Royal Navy scientific survey vessel HMS Challenger docked at Tristan to conduct geographic and zoological surveys on Tristan, Inaccessible Island and the Nightingale Islands. In his log, Captain George Nares recorded a total of fifteen families and eighty-six individuals living on the island. Tristan became a dependency of the British Crown in October 1875. On 27 November 1885, the island suffered one of its worst tragedies after an iron barque named West Riding approached the island, whilst en route to Sydney, Australia from Bristol. Due to the loss of regular trading opportunities, almost all of the island's able-bodied men approached the ship in a lifeboat attempting to trade with the passing vessel. The boat, recently donated by the British government, sailed despite rough waters and, although the lifeboat was spotted sailing alongside the ship for some time, it never returned. Various reports were given following the event, with rumours ranging from the men drowning, to reports of them being taken to Australia and sold as slaves. In total, 15