(2015) Wheal Busy: Scheduled Monument conservation

Wheal Busy forms part of the World Heritage Site through its importance to tin and copper mining during the 18th and 19th centuries and is also one of the historic mine sites on the Mineral Tramways Coast to Coast Trail, which links Devoran in the south with Portreath to the north. 

The extensive conservation work at Wheal Busy detailed in the previous edition of Cornish Mining is now complete, which was facilitated by Natural England’s land management team in Cornwall, working in partnership with the landowners the Tregothnan Estate. The works were funded through a Higher-Level Stewardship agreement. 

Wheal Busy is thought to have its origins in the latter 1600s and during the following two centuries the mine was to experience important innovations in steam pumping technology. A Newcomen Atmospheric Engine was put to work by around 1726 and a Smeaton improved atmospheric engine was on site by the latter 1770s. The renowned Scottish engineer James Watt was also to personally oversee the installation of the first Boulton & Watt separate condenser engine to work in Cornwall, which started in September 1777. Watt was accompanied by his wife Ann on the trip to Cornwall, who noted of the mine that the “The face of the earth is broken up in ten thousand heaps of rubbish and there is scarce a tree to be seen.” Hopefully Ann would be impressed to learn that today the mine has international importance as part of a World Heritage Site.

The conservation consultants PWH secured the contract to oversee the building renovation which has seen extensive repairs to the impressive Cornish high-pressure type pumping engine house, dating from 1856, along with its associated chimney and boiler house. The latter is a rare survival as it retains its original roof timbering. The importance of Wheal Busy was first acknowledged nationally in 1974 when it was designated as a Scheduled Ancient Monument.

This engine house, as is the case with many others across Cornwall, has held more than one engine during its operational lifetime, as the mine sett (the area leased from the landowner) was reworked by successive companies. A Harvey’s Hayle Foundry engine with an 85-inch diameter steam cylinder was first installed in 1856, this pumping from the Engine Shaft for 10 years until the partial closure of the mine in 1866. The house was next occupied by the Perran Foundry 90-inch cylinder machine in 1872, this working for only six months before being decommissioned in July the following year. Finally, a reconditioned 85-inch cylinder Perran engine was installed c.1909, this working until 1924. As was often the case with large beam engines on redundant mines in Cornwall, this was to stay unused in its house as there was no longer a commercial demand for steam pumps in mining. The engine was left to deteriorate and only succumbed to the attentions of the scrap man 28 years later, in 1952.  

Careful inspection of the engine cylinder bedstones (its foundation) reveals that these were most probably left in situ and reused from the brief working of the 1870s. The scaffolding erected to enable the consolidation of the chimney and engine house also afforded an excellent ‘aerial’ view of the bedstones and this revealed that these have been modified at some stage. Two of the five original circular holes cut to accommodate the cylinder hold-down bolts appear to have been rather crudely reshaped, using a series of adjoining drill steel holes. Presumably this modification was sufficient to accommodate the smaller 85-inch cylinder machine at the time of the final working.      

The site consolidation works were undertaken by the conservation builders Kingston Construction Ltd., which commenced work in early August 2014. Following the careful clearance of vegetation and tree ivy the boiler house was the first to receive attention with the extensive rubble-built walls being re-pointed using a tested and approved lime-based mortar, chosen to match the original. The adjoining engine house and adjacent chimney were to be tackled next, with the repair to the boiler house roof being one of the last jobs undertaken. Here most of the original timbers survived intact though some joints of the roof trusses had rotted where water had penetrated the corrugated iron roof covering. Fortunately, new timber was able to be scarf jointed onto the existing truss ends thereby preserving as much of the original fabric as possible.

Brickwork within the chimney and engine house also needed attention and for the former, the upper courses required careful resetting where the mortar had been substantially lost. The red brick arch to the cylinder door at the rear of the engine house probably required the most work overall however, as the inner courses had been lost causing cracking of the adjacent structure. Kingston and their building subcontractors, from Redruth, were tasked with the careful, staged, dismantling of the arch, which was then reconstructed using matching site-won bricks from elsewhere, when required.        

The work now complete forms part of a ten-year Higher-Level Stewardship agreement between the Tregothnan Estate and Natural England, which has seen some £280,000 allocated to undertake the works at Wheal Busy and to enhance natural habitats across the site. Carpenters of the Tregothnan Estate also made a significant contribution to the project by constructing replacement windows and doors for the boiler house - skilfully matching these with surviving timberwork and features shown in historic photographs.

More recently news of the conservation work has come to the attention of Fuji Television in Japan. Fuji TV journalist and presenter Ayaka McGill visited Wheal Busy from London in June, to film a news piece on the restoration of the brickwork within the engine house and chimney. Fuji TV are highlighting Japan’s bid for World Heritage Site status this year for the ‘Sites of the Meiji Industrial Revolution’, which includes several nineteenth century brick-built structures.

While on site Ayaka and her colleagues had the opportunity to meet with Matt Vale of the project management team PWH Conservation Consultants, and also David Wilkinson and Tony Lambert of Kingston Construction Ltd., who were able to explain in detail how decaying brickwork is assessed and repairs made to affect a historically appropriate conservation. Terry Herron of Tregothnan was also on hand to set out the Estate’s support, and its substantial involvement in the project. 

Wheal Busy is the latest in a number of World Heritage Site conservation projects to be generously funded through a Higher Level Stewardship agreement and the World Heritage Site Partnership Board thanks Natural England, the Tregothnan Estate, PWH Conservation Consultants, Kingston Construction Ltd., Cornwall Council Strategic Historic Environment Service, and Historic England, for their considerable support.

Specifically, thanks are extended to Ann Reynolds (Cornwall Council Senior Archaeologist); Simon Leather and Nick Coley (Tregothnan Estate); Matt Vale and Shaun Watts (PWH Conservation Consultants); Ann Preston-Jones (Historic England); and last but certainly not least, Beth Tonkin and Hugh Tyler (Natural England) for without their continued support it would not have been possible to secure such an excellent outcome.

Ainsley Cocks, 2015