Summary

A tin mill 30m north of the confluence of Dry Lake and River Erme.

Source: Historic England

Details

This record was the subject of a minor enhancement on 11 November 2015. The record has been generated from an "old county number" (OCN) scheduling record. These are monuments that were not reviewed under the Monuments Protection Programme and are some of our oldest designation records.

The monument includes a tin mill situated on the northern bank of Dry Lake close to its confluence with the River Erme. The tin mill survives as a small rectangular drystone building measuring up to 5.5m long by 3.8m wide internally. The walls survive differentially and measure up to 0.7m wide and 1.9m high although in several places they are considerably lower. The building is terraced into the slope. The eastern end of the north wall is thicker and may be slightly raised for a launder to take water to the wheel pit which is preserved as a buried feature. A leat leads towards the building from several hundred metres upstream off the River Erme. A mortar stone was found in the bed of the River Erme some distance downstream and is thought to have come from this building. However, no mould or mortar stones are currently visible in or around the structure. The tin mill lies within an extensive area of tin working.

Source: Historic England

Reasons for Scheduling

Dartmoor is the largest expanse of open moorland in southern Britain and, because of exceptional conditions of preservation, it is also one of the most complete examples of an upland relict landscape in the whole country. The great wealth and diversity of archaeological remains provide direct evidence for human exploitation of the Moor from the early prehistoric period onwards. The well-preserved and often visible relationship between settlement sites, major land boundaries, trackways, ceremonial and funerary monuments as well as later industrial remains, gives significant insights into successive changes in the pattern of land use through time.

Blowing mills (also known as blowing houses) survive as rectangular drystone buildings served by one or more leats and are characterised by the presence of granite blocks with moulds cut into them - bevelled rectangular troughs known as mould stones - and on occasion by the square or rectangular stone built base of the furnace itself. During the medieval and early post-medieval period, black tin (cassiterite) extracted from streamworks and mines, was taken to blowing mills to be smelted. During the same period tin ore was taken to stamping mills to be crushed, using heavy iron-shod stamps attached to the lower end of vertical wooden posts called lifters, which were raised using a water-driven rotating axle. Thus raised, the stamps fell under gravity onto the ore, crushing it between the stamp's head and a hard slab of rock called the mortar stone. In some circumstances the exact nature of the mill is unclear from visible surface evidence alone and the more general term tin mill is then applied.

Despite differential preservation the tin mill 30m north of the confluence of Dry Lake and River Erme survives comparatively well and its location within an extensive area of tin working is an important economic juxtaposition. Tin working of any kind is limited in Britain to Devon and Cornwall. The tin mill will contain archaeological and environmental evidence relating to its construction, function, longevity, abandonment and overall landscape context.

Source: Historic England

Sources

Books and journals
Butler, J, Dartmoor Atlas of Antiquities, Volume Four – The South-East , (1993)

Source: Historic England