This walk was planned for 25th April but it was cancelled due to the Coronavirus lockdown. Parking should have been in Postbridge main car park or in the car park across the road in Bellever Forest.  The former might have been difficult because of the builders’ vehicles present while the Visitor Centre is rebuilt. As it was, there was a free layby near the Lich Way Gate along the road from Higher Cherry Brook car park towards Postbridge.

 

The Lich Way gate ….. see Legendary Dartmoor: Lych Way – The Way of the Dead. This was re-routed 1999 because the old track had become very “mirey”.

 

Notice on the gate.

 

The “new” Lich Way path, with Arch Tor at the top right …..

 

Zoomed view to Arch Tor, SX 6336 7817, the top stone is a large logan stone, with rock basins and an inscription that reads “PC” – it has been suggested that this refers to Powdermills Cottages.

 

On reaching the Powdermills site, after about a 1 km (o.6 mile) walk, there is a gate with the view above as you approach it. This shows the first of three Incorporation Mills where gunpowder was initially prepared between grinding stones powered by a waterwheel in the middle of the building. The site was powered by a leat initially from the Cherry Brook, without permission, and later also from the East Dart, after permission was granted.

 

Notice on the gate entering the site.

 

View of the North Chimney on entering the site, there is another building complex on the hill behind the trees.

 

Another view of the first Incorporation Mill, with a DNPA notice on the guard around the water wheel pit …..

 

The notice – this is shown below in three images for easier reading …..

 

First section …..

 

Second section …..

 

Third section.

There is no known map saying what each building was used for, so there is conjecture based on the gunpowder-making processes and  the requirements for them to be carried out. Describing the site is a little difficult because there are two main references:

(1) Drew Campbell (2019), Powdermills – The Story of the Dartmoor Gunpowder Factory, Blackingstone Publishing, Moretonhampstead, Devon. 128 pages. References below are building numbers without brackets, and …..

(2) Andrew R Pye & R Robinson (1990), An archaeological survey of the gunpowder factory at Powdermills Farm, Postbridge, Devon (1990). This has not been obtained or examined but is referred to extensively in the Devon & Dartmoor HER – MDV5913 – Powder Mills Gunpowder Factory, Cherry Brook record with links to all the features described below. References below are numbers in (brackets).

There are said to be 18 buildings and the real awkwardness arises from the archaeological survey starting with Building 1 at the top of the site, whereas the book starts from the south end (near Powdermills Cottages) with Building 1.

Gunpowder, black powder or  rock powder (local name) used for quarrying and mine blasting, is still used in fireworks. The composition is 75% saltpetre, 15% charcoal and 10% sulphur (aka brimstone or burning stone).

 

The walk is now described walking from the south end of the site walking to the north end and the entry / exit gate.

Having walked down the gentle slope from the gate to the bottom of the site we see the South Chimney, linked to a complex building behind it by a covered flue with other buildings beyond, across the main track. There is also a small building under the trees up the slope behind the chimney. This is 17 (18) South chimney / Cylinder House  / Charcoal / Saltpetre Works: group of buildings including a possible cylinder house, for charcoal manufacture. If ready-made charcoal was brought in, then this could have been for processing saltpetre, dissolving it and recrystallising it to make it more pure. Three phases of development and extension have been identified and it is likely that the function of the buildings changed over time. A flue and chimney indicate heat was involved. The flue to the chimney is about 1 metre deep and ½ metre wide. Its eastern portion is now open and rubble-filled, but the western portion is still capped. It enters the base of the chimney which is set on a plinth. The chimney is about 10.5 metres high.

 

A view of the South Chimney showing the now-partially covered flue.

 

2 (17) Watch House / Cartridge Press House / Store – possible saltpetre crystallising house. Long rectangular single-storey building located at the southern end of the site and aligned north to south. Two, possibly three, phases have been identified. Water was culverted through the building under the floor. Its north wall was probably the dwarf wall which now subdivides it from the extension to the north. Dwarf walls in one interior consist of one long spine wall and two side walls. Another dwarf wall runs east to west across the structure from the northernmost door to the east wall. These appear to form a raised floor with water, air or heat circulating beneath. A small, square, stone-lined feature to the west of the south-west corner may be a well, or possibly a pit in which staves were soaked. The building is described in the book as the Watch House, where materials in and out of the site were monitored. It might also have been used as a store. The building up on the hill is 1 (16) Checking House or possible office or store. This is a small, rectangular, ruin off the track, to the left of the site entrance gateway. It could have been used for checking workers into the works to ensure they had nothing about them that might cause sparks.

 

A last view of 2 (17) Watch House / Cartridge Press House / Store, with the South Chimney and its associated buildings across the Cherry Brook. The South Chimney and the track coming across the Cherry Brook with its clapper bridge are visible in the background.

 

4 (14) x 2 – a double building with two waterwheels. Incorporating/composition mill (south), possible cartridge press house (south ½ of N building) and possible corning/dusting house/glazing mill (north ½). Consists of two pairs of structures on either side of two wheelpits. The tailrace of the southern wheepit discharges back to the Cherrybrook. The wheel between the southern mill was powered by a continuation of the leat powering buildings to the north. The wheelpit tailrace discharged via a channel into Cherry Brook. The culvert has an arched roof of granite blocks overlain by slabs …..

 

The southern wheelpit in the building above.

 

A view of the Cherry Brook and clapper bridge.

 

12 (12) Breaking House: Small building, aligned north to south just south of the glazing mill (below). There is a large rectangular stone table, 20-25 centimetres thick, on a masonry base.The table top is smooth. On this, the slabs of pressed gunpowder were broken down. The rear wall on the left appears to be rendered.

 

13 (11) Glazing Mill: Long rectangular building, aligned north / south. The structure contains supports for a raised floor, or to support machinery such as glazing barrels. The internal supports may alternatively have been to provide under-floor ventilation. There is a wheelpit at the south end of the building. This where “broken” pieces of gunpowder from the Breaking House were sieved and large pieces were returned to the Breaking House and fine powder was returned to the Press House.

There is a Circular Reservoir on the hill above between this building and the preceding building.

 

16 (9) Final Preparation Rooms: It is probable that these buildings were used for dusting, glazing, sieving and packing the gunpowder prior to carting it it off-site. Horses may have been stabled here as well as barrels and other materials being stored here. There are two mills powered by a waterwheel, seen from “behind” the North Chimney …..

 

A view of the three Incorporation Mills ….. two are gable-ended and one is square-ended. The main track in and out of the site is seen curving around at the upper right of the image.

 

15 (7) Gunpowder Drying House:  ‘gloom’ or steam stone used for drying gunpowder. A portion of the west wall of “Unit D” (in the survey) remains, in the centre of which is a flue leading to the North Chimney which is 5-6 metres to the south-west. Two wheel cogs lie at the east end of the building, but may not be in situ. 

 

7 (3) Incorporating Mill: Similar in plan to ‘Buildings 1 and 2’, consisting of two units flanking a central wheelpit. The wheelpit is largely filled with rubble. The wheel was powered by water from the tailrace of the wheelpit of ‘Building 2’. The three incorporating mill houses (“Wheelhouses”) were of massive construction with many granite blocks being 6-feet long and the was about 6-feet thick, to withstand inadvertent explosions. The roofs were very flimsy, of wood and tar, to blow off without damaging the main structure. They could be replaced easily.

 

From the “rear” – this is the third incorporating mill in the system in that the water comes from the mills above here on the hill. The raised bank bringing the water to a launder to reach the water wheel is seen at the right …..

 

Looking into the central wheelpit …..

 

6 (2) Incorporating Mill showing the outflow leat …… this feeds the third mill, shown above.

 

Foreground: 8 (4) Powder Magazine: A small rectangular stone structure, approximately 4 metres by 2.5 metres, completely ruined. There is a magazine associated with each of the mills plus other possible magazines on the site.

Background: 5 (1) Incorporating Mill: Consists of a pair of gable-ended structures flanking a large central wheelpit. Both of massive granite blocks with walls about 2 metres thick at their bases. Tar dribbles indicate original roofing was of tarred tarpaulin or wood. The wheelpit is aligned north-east to south-west and runs the whole width of the units. Wheel axle appears to have projected into their ground floors. Powered by a launder to the north-east which flowed out through a culvert to the south-west. This is roofed for 3.5 – 4 metres, then becomes an open channel which runs downhill to feed the reservoir belonging to ‘Building 2’.  The raised bank at the left brought the leat that fed a launder to the waterwheel.

 

General view of the North Chimney and 16 (9) Final Preparation Rooms.

 

The raised bank at the right brought the leat.

 

Looking into the wheelpit of Incorporation Mill number 1, seen from the uphill side.

 

Ponies encountered on the track back to the car.

Satellite map + GPS track of the 15th May reconnaissance walk – just after lockdown was eased on 13th May

More photographs on the Dartmoor CAM web site