s, mining seems to have prospered,
with one or two intervals of great depression, and as late as 1861
seventy-four mines were being worked in Devonshire. 'Streaming' for tin
was very much practised in the Middle Ages, and the sides of valleys all
over Dartmoor are scored with the works of the tin-streamers, who turned
about the streams and examined the beds for 'grain-tin.' Many of the
ruined 'blowing-houses' are still to be seen on the moor. Mrs. Bray
mentions a curious testimony to the wildness and remoteness of the parts
in which some of the miners must have worked: 'A very old woodcut ...
exhibited a whole pack of hounds harnessed and laden with little bags of
tin, travelling over the mountains of Dartmoor; these animals being able
to cross the deep bogs of the forest in situations where there were no
roads, and where no other beasts of burden could pass.'

It was owing to the mines that Dartmoor became a part of the Duchy, for
the 'metalliferous' moors of Dartmoor and Cornwall had, on that account,
long been Crown lands; and therefore, when Edward III created his eldest
son Prince of Wales and Duke of Cornwall, the Chase of Dartmoor, and the
Castle and Manor of Lydford were granted to him with the estates in
Cornwall. Dartmoor has existed as a forest practically from time
immemorial, and the date when forest laws were first imposed on it is,
in the opinion of the learned, 'lost in antiquity.' The first charter
affecting the state of the moor was bestowed in 1204, when King John was
compelled reluctantly to grant a Charter of Forests, disafforesting the
lands that had been gradually appropriated by the Kings since Henry I.
Surrounding the forest proper are lands known as the Commons of Devon,
and, usually speaking, they are included in any general reference to
Dartmoor. Every parish in Devonshire, excepting Barnstaple and Totnes,
has a right to pasture cattle on them for the payment of a small sum.
Two classes of men have special rights in the moor: owners and occupiers
of tenements within the forest, and venville tenants, or owners of land
in particular vills, or towns, adjoining the forest. Claims and
counter-claims as to their exact rights and liabilities have been
pressed in successive centuries, but various ancient documents set forth
these tenants' rights, 'time out of mind, to take all things that might
do them good, saving green oak and venison.' These privileges include
pasturing all 'commonable beasts' on t