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Summary

Leat running from the prison to land at Tor Royal. Also known as Bachelors Hall Mine Leat. Foul Leat was constructed in the early 19th century to convey sewage effluent from the Princetown War Prison to Tor Royal Newtake probably to fertilize the pasture on Royal Hill. It is on the contour very close to and just higher than the Devonport Leat which in fact it crossed at one place.

Location

Protected Status

• SHINE: Earthwork and structural remains of a section of the late 18th century Devonport Leat running from Nun's Cross to Princetown including extensive tinning remains at Whiteworks Tin Mine

Other References/Statuses

• National Monuments Record: SX67SW196
• National Record of the Historic Environment: 619885
• Old DCC SMR Ref: SX67SW/133

Monument Type(s) and Dates

• LEAT (XVIII to XIX - 1800 AD (Between) to 1809 AD (Between))

Full description

Untitled Source (Migrated Record). SDV265772.

Des=dnp survey (6") of tor royal farm/(1982)in smr. Leat shown on dnp tor royal survey - runs sx61077243 to sx61457215 (dnp).

Shillibeer, W., 1805-1818, Map of Freehold and Enclosures on Dartmoor, 1805-18 (Cartographic). SDV218725.

South West Heritage Trust, 1838-1848, Digitised Tithe Maps and Transcribed Apportionments (Cartographic). SDV359954.

The 1839 Tithe Map depicts more or less the same route but also shows its complete course from the bifurcation on the west side of Royal Hill, its line around both flanks of the hill to the meeting point near the head of the Lanson Brook.

Gill, C. (ed.), 1970, Dartmoor: a New Study, 262 (Monograph). SDV161800.

Robins, J., 1983, Follow the Leat, 54 (Monograph). SDV352718.

?/follow the leat/(1983).

Hemery, E., 1983, High Dartmoor, 390 (Monograph). SDV249702.

Royal Commission on the Historical Monuments of England, 1985, Aerial Photograph Project (Dartmoor) - Dartmoor Pre-NMP (Cartographic). SDV319854.

Not visible.

Royal Commission for the Historical Monuments of England, 1987-1993, Duchy Farms Project Survey Visit (Report - Survey). SDV350839.

(21/04/1989) Foul Leat was constructed in the early 19th century to convey sewage effluent from the Princetown War Prison to Tor Royal Newtake probably to fertilize the pasture on Royal Hill. It is on the contour very close to and just higher than the Devonport Leat which in fact it crossed at one place giving rise surely to problems of occasional pollution.
An early 19th century Duchy map (1805-1818) depicts its course from the Blackbrook River, presumably the source of fresh flowing water into the north-east side of the prison enclosure out of the S side across a stream to the N boundary of Tor Royal (house); midway it is annotated "Foul Leat (1812) or Bachelors Hall Mine Leat (1806)". From Tor Royal its sinuous route crosses the Devonport Leat and runs around the S side of Royal Hill apparently cutting through a series of ditched field plots on the way. Here it is annotated "Foul Leat" and was presumably unfinished.
The 1839 Lydford Tithe Map depicts more or less the same route but also shows its complete course from the bifurcation on the W side of Royal Hill, its line around both flanks of the hill to the meeting point near the head of the Lanson Brook (Gill, 1970 and Hemery, 1983, and Robins, 1983).
Foul Leat can be traced for much of its course from Dartmoor Prison to the E flank of Royal Hill. Short stretches have been either effaced or ploughed down but elsewhere, now dry and silted, it is on average 0.7m wide and 0.3m deep, with a slight earthen bank on the downhill side.
From the prison to the crossing point of a small stream (SX 58977369) in prison property it was not investigated. From here to the road
(SX 59337396) it has been effaced by agricultural activity. It then follows the 405m contour along the upper side of a field bank, through the Bachelors Hall Tin Mine complex (SX 59817346) (where at some time it has been breached) across the cultivated inbye fields to the rear of Tor Royal (SX 59907313). It runs along and down a steep east slope through woodland to the lip of a quarry (SX 67 SW 195) where its course is confused by shallow drainage ditches. At the foot of the quarry scoop at 396m a well-constructed causeway 4.9m wide and a maximum 1.3m high, faced with coursed moorland stoned, indicates the line to where it crossed the Devonport Leat (SX 60167244), probably by a wooden launder. Beyond, its course across low-lying marshy ground to SX 60447280 is represented by a c.2.0m wide slightly raised peat strip with some stones and boulders, bounded by peat-cutting headlands. The effluent was conveyed across this marsh presumably also by a wooden launder. It bifurcates at SX 60447281 and skirts both flanks of Royal Hill, occasionally winding its way through dense patches of earthfast boulders, to terminate at 387m in the silted headwaters of Lanson Brook, at SX 61867225.

Joy, R., 2002, Dartmoor Prison A Complete Illustrated History Volume 1 The War Prison 1809-1816 Parcere Subjectis, 28-30, figures (Monograph). SDV359842.

Water supply to the war prison was established by 1809 and was in use until the 1990s, when it was disconnected. A water course was surveyed and built, running from Spriddle Lake, a tributary of the River Walkham (SX585803) about four miles from the prison, finishing up at the reservoir outside the gates of the prison (MDV27089). From the reservoir (MDV42843), water was fed into a round water tower, inside which were five bibcocks (A-E) which controlled the water, as required, into five open leats that then flowed into different parts of the prison. These fed out into the foul water leat, which collected foul water from the slaughterhouse and then proceeded to Tor Royal and was distributed over the land below a hill called Broken Barrow. The final part of the foul leat on prison land, nearest its exist from the war prisons, was filled in by contractors laying new drains in the 1980s.

Stanbrook, E., 2002, Dartmoor's War Prison & Church 1805-1817, 85-6 (Monograph). SDV359848.

There were problems with setting up of the foul water leat from the prison. In 1808 Thomas Tyrwhitt, who was interested in using the 'foul water' from the prison to fertilising his lands at Tor Royal, applied to the prison Board to get it diverted. Originally the plan had been to divert it to the Blackabrook, channelling over or under the Devonport Leat. After some argument and negotiation, Tyrwhitt was able to get his way. Parts of the dry course of the leat can still be traced.
Both least were troubled during the first few years; bad weather caused them to freeze solid in 1809 and a year later they were in such a bad condition that they required deeper digging and lining with bigger stones. By October 1810, it was decided to lower the clean water course and have it covered.

Sources / Further Reading

Associated Monuments

Associated Finds: none recorded

Associated Events

• EDV8628 - Tor Royal Farm Duchy Farms Survey
• EDV8629 - Peat Cot Farm Duchy Farms Survey
• EDV8664 - Torgate House, Duchy Farms Survey
• EDV8666 - Tor Royal Plantation, Duchy Farms Survey
• EDV8409 - Dartmoor Royal Forest Project
• EDV8714 - Survey of Dartmoor Prison Farm

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