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Summary

Mid-19th century cast iron aqueduct carrying the Tavistock Canal over an old track (Deep Lane) at Shillamill. The track was later abondoned.

Location

Protected Status

• SHINE: Structures, earthworks and below-ground mining features associated with Wheal Crebor Mine including a former canal and railway, east of Buctor Farm

Other References/Statuses

• SHINE Candidate (Yes)

Monument Type(s) and Dates

• AQUEDUCT (Constructed, XIX - 1839 AD to 1839 AD (Between))

Full description

Cornish, G., 2007, Note on the Shillamill Aqueduct (Personal Comment). SDV339129.

The canal aqueduct at Shillamill is an iron channel stamped with the date 1839 and the makers name 'Gill'. The towpath is supported on thin slates on slender cast iron beams. Other details: Photographs.

Buck, C., 2013, Tavistock Canal, Devon: Archaeological Impact and Recording Report, 11, 15-16; Figures 4, 12-14 (Report - non-specific). SDV356300.

Following a structural survey in 2011, it was recommended that a rusty wrought iron support below the towpath be replaced by a modern equivalent, and that the tall retaining wall on the south-west side of the aqueduct bridge be repointed and structural ties inserted to strengthen a structural crack in the masonry. Work was started in May 2012, and also included removal of a tree growing out of the west side of the north end of the aqueduct bridge. At the north end of the structure, under the aqueduct section, it appears that water has been leaking, and consequently the foundations masonry and pointing in this area have softened to the extent that the masonry is collapsing and arching downwards. Also, the steps that allowed access from the towpath down into the adjacent field have badly deteriorated, and need to be rebuilt.

Buck, C., 2015, Buctor Farm, Tavistock (Report - Assessment). SDV359746.

This study was commissioned by the landowner on behalf of Natural England as part of a Higher Level Environmental Stewardship Agreement Scheme and produced by Cornwall Archaeological Unit, Cornwall Council.
The aqueduct bridge (Fig 25) carries the canal over an access lane to fields north of Shillamill Farm – this had been cut by construction of the canal in 1803. The iron plated trough structure seen today was built in 1839 by Gill & Co of Mount Foundry, Tavistock, replacing an earlier structure. As part of the Tamar Valley Mines Heritage Project structural survey on this building (2009), one of the four wrought iron lintels (over the towpath section on the south side of the canal), was replaced, and some re-pointing to the side and base walls undertaken (Buck 2013, 11).
Survey: The bolted sections of the iron trough that carries the canal water over what is now a cattle creep (formerly a road track), extends to either side of the granite quoined masonry, supported by four wrought iron lintels (widening into the masonry sides) set into the granite masonry (Fig 25). Three other similarly styled lintels provide the support for large slates under the tow path on the south side of the canal. The middle lintel however had rusted to the extent of being ineffectual, and was subsequently replaced with an equivalent (Buck 2013, 11). Unfortunately, the canal has been leaking for a number of years, which has caused the foundation masonry to drop – causing sagging to the entire structure – and causing stone to crack and mortar pointing to crack and dissolve.
Significance: High
This site has a High significance rating, given its site history, its impact upon the landscape and its designation as being part of the Cornwall and West Devon World Heritage Site. The tunnel portal and tunnel itself are Listed Buildings (Grade II).
Recommendation: Site should be retained after any obscuring vegetation clearance. If there is to a site interpretation strategy for this higher stewardship scheme, this could include the provision of an interpretation panel, for example near Site 52.1, (near the towpath and overlooking the site of the Wheal Crebor water wheel), a viewpoint perhaps towards Wheal Crebor mine across the Lumburn Valley. The provision of occasional guided tours around Wheal Crebor Mine could also visit this impressive feature.

Waterhouse, R., 2017, The Tavistock Canal. Its History and Archaeology, 75-79, 322, 351-355, figs 4.1-4.7, 10.13, 10.56-10.61 (Monograph). SDV361789.

The Shillamill Aqueduct is located on the southern extremity of the loop of the canal between Crowndale and its crossing of the Lumburn Valley. One of the most unexpected structures on the canal, it is a small cast iron trough aqueduct dated ‘1839’ on its bolted sided plate and also has the makers mark; ‘Gill & Co.’ noted. It bears the coat of arms of the Duke of Bedford twice on each side of the aqueduct, as well as imitation saltaire cross-shaped strengthening ribs and bosses of the type typically found on the side plates of water storage tanks.
The aqueduct now spans a cattle creep beneath the canal, but originally was built to cross a public road known as Deep Lane, which was abandoned in 1883 (still partly visible on the 1880s historic map).
It appears that there was an overbridge (probably a timber lifting bridge) here before the aqueduct was constructed and the plans of the canal before and after 1835 show the original course ran slightly to the north of the present course. Unclear why the bridge was replaced with a more expensive aqueduct; the origins of which are unknown. It's not referred to in the company account books or annual reports.
Waterhouse includes detailed drawings of the end plates, as well as sections and plans of the aqueduct.
Cast iron aqueducts are nationally rare, with only about 35 examples surviving. This aqueduct is an impressive example of the ability of Gill & Company's Mount Foundry to produce technically advanced castings before the advent of the copper-mining boom of the mid-19th century.

Sources / Further Reading

Associated Monuments

Associated Finds: none recorded

Associated Events

• EDV6413 - Archaeological Monitoring at Tavistock Canal Aqueduct Bridge
• EDV7058 - Archaeological Management Plan, Buctor Farm, Tavistock (Ref: 2015R055)

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