Encyclopædia Britannica, Ninth Edition/Tristan da Cunha

TRISTAN DA CUNHA, a group of three small volcanic islands, situated in the South Atlantic nearly midway between the Cape of Good Hope and the coast of South America, the summit of the largest being in 37° 5′ 50″ S. lat. and 12° 16′ 40″ W. long. They rise from the low submarine elevation which runs down the centre of the Atlantic and on which are likewise situated Ascension, St. Paul's Rocks, and the Azores; the average depth on this ridge is from 1600 to 1700 fathoms, while depths of 3000 fathoms are found on each side of it. The depth between the islands is in some places over 1000 fathoms. Tristan, the largest and northernmost island, is nearly circular in form, about 7 miles in diameter, with a volcanic cone in the centre (7640 feet). Precipitous cliffs, 1000 to 2000 feet in height, rise directly from the ocean on all sides, except on the north-west, where there is an irregular plain, 100 feet above the sea, and 2 miles in length and mile in breadth. The crater of the central cone is said to be filled with a freshwater lake which never freezes. Inaccessible Island, the westernmost of the group, is about 20 miles from Tristan. It is quadrilateral in form, the sides being about 2 miles long. The highest point (1840 feet) is on the west side; all round there are perpendicular cliffs 1000 feet in height. At the base of these are in some places narrow fringes of beach a few feet above the sea-level. Nightingale Island, the smallest and most southern of the group, is 10 miles from Inaccessible Island. Its coasts, unlike those of the other two islands, are surrounded by low cliffs, from which there is a gentle slope up to two peaks, the one 1100 feet, the other 960 feet high. There are two small islets Stoltenkoff (325 feet) and Middle (150 feet) and several rocks adjacent to the coast. The rocks are feldspathic basalt, dolerite, augite-andesite, sideromelane, and palagonite; some specimens of the basalt have porphyritic augite. The caves in Nightingale Island indicate that it has been elevated several feet. On almost all sides the islands are surrounded by a broad belt of kelp, the gigantic southern sea- weed (Macrocystis pyrifera), through which a boat may approach the rocky shores even in stormy weather. There is no good or safe anchorage. The beaches and lower lands are covered with a dense growth of tussock grass (Spartina arundinacea), 8 to 10 feet in height, which shelters millions of penguins (Eudyptes chrysocoma), which there form their rookeries. There is one small tree (Phylica nitidct), which grows in detached patches on the lower grounds. Independently of introduced plants, fifty-five species have been collected in the group, twenty- nine being flowering plants and twenty-six ferns and lycopods. A majority of the species are characteristic of the present general flora of the south temperate zone rather than any particular part of it: botanically the group is generally classed with the islands of the Southern Ocean. A finch (Nesospiza acunhee), a thrush (Nesocichla eremita), and a water hen (Gallinula nesiotis) are the only land birds the first two being peculiar to the islands. In addition to the penguins numerous other sea birds nest on the islands, as petrels, albatrosses, terns, skuas, and prions. One or two land shells, a few spiders, several Coleoptera, a small lepidopter, and a few other insects are recorded, but no Ortlioptera or Hymenoptera. The prevailing winds are westerly. December to March is the fine season. The climate is mild and on the whole healthy, the temperature averaging 68 Fahr. in summer, 55 in winter, sometimes falling to 40. Rain is frequent; hail and snow fall occasionally on the lower grounds. The sky is usually cloudy. The islands have a cold and barren appearance. The tide rises and falls about four feet.

The islands were discovered and named by the Portuguese in 1506. The Dutch described them in 1643. D Etcheverri landed on them in the year 1767, when he gave Nightingale and Inaccessible Islands their names. Their exact geographical position was determined by Captain Denham in 1852, and the "Challenger" completed the exploration of the group in 1873. When first dis covered the islands were uninhabited. Towards the end of the 18th and in the beginning of the 19th century several sealers resided on them for longer or shorter periods. In 1816 the islands were taken possession of by Great Britain. In 1817 the garrison was withdrawn, but Corporal William Glass, his wife and family, and two men were allowed to remain. This small colony received additions from time to time from shipwrecks, from whalers, and from the Cape of Good Hope. In 1826 there were 7 men and 2 women besides children. In 1873 there were 84 inhabitants, in 1886 97. They possess cattle, sheep, and geese. There are usually good potato crops. The settlement has always been on the flat stretch of land on the north-west of Tristan, and is called Edinburgh. Two Germans lived for several years on Inaccessible Island, but with this exception there have been no settlements either on this or on Nightingale Island.