DARTMOOR, high plateau, in south-west Devonshire, Eng land. It is 23 m. from north to south, 20 m. from east to west, 200 sq.m. in area with a mean altitude of 1,50o feet. It is the highest and easternmost in a broken chain of granitic elevations which extends to the Scilly isles. The higher parts are open, bleak and wild. Sloping heights rise from the main tableland, crested with broken masses of granite, locally named tors. The highest of these are Yes Tor and High Willhays (2,028 and feet). Large parts of the moor are covered with morasses; and head-waters of all the principal streams of Devonshire (q.v.) are found here. Only two good roads cross the moor, one between Exeter and Plymouth, and the other between Ashburton and Tavistock, intersecting at Two Bridges. The central part of Dartmoor was a royal forest from a date unknown, probably before the Conquest. Its woods were formerly more extensive than now, but a few small tracts of dwarf oaks remain in the lower parts. Previous to 1337 the forest had been granted to Richard, earl of Cornwall, by Henry III., and from then has belonged to the Duchy of Cornwall. The districts immediately surrounding the moor are called the Venville or Fenfield districts. The holders of land by Venville tenure have rights of pasture, fishing, etc., in the forest. (For antiquarian remains see DEVON.) Princetown prison was built in 1809 to house French prisoners, and was adapted for use as a convict station in 185o. A tract of moorland adjacent to the prison has been brought under culti vation by the inmates.