The Cornish Engine House

The principal function of an engine house was to provide the integral framework of the engine it contained and its basic design was essentially established by Newcomen for his Atmospheric Engine. The distinctive architecture of Cornish beam engine houses links their landscape context - both in the United Kingdom and overseas - with Cornwall and West Devon mining engineering. More beam engines were installed in Cornwall and West Devon than any other mining region of the world: a total of around 3,000 engine houses were built to house them.

East Pool Mine (A5, 1887, Listed Grade II*). The North Whim at Mitchellís Shaft was designed by Francis Michell of Redruth and made by Holman Brothers of Camborne in 1887. It was the last traditional Cornish beam whim to be built and is now preserved by the National Trust. © Barry Gamble. South Phoenix Mine (Listed Grade II). Housemanís engine house was once converted into a mine office. © Barry Gamble. Wheal Enys (1852), Wendron. Sympathetic conversion. © Barry Gamble. Gunnislake Clitters Mine (Scheduled Monument, Listed Grade II). Some mines are located in the Tamar Valley itself and here the topography imparts an unusual character, some having been worked beneath the river bed. This engine house pumped river water for dressing purposes. © Barry Gamble. Wheal Coates, Towanroath Shaft (1872, Listed Grade II). The pumping engine house of this tin and copper mine is pictured. Its deeper levels ran out beneath the sea. © The National Trust. Tregurtha Downs Mine (1882, Listed Grade II), Goldsithney. The massive engine house at St Aubynís Shaft contained an 80-inch pumping engine that had a working life not untypical for Cornish engines: The engine was originally commissioned from the Copperhouse Foundry (Hayle) in 1853 for Great Wheal Alfred in Gwinear. It was subsequently moved to nearby Crenver and Wheal Abraham in 1864 and then to Tregurtha Downs in 1882 where it worked until 1897. It was purchased by South Crofty Mine in 1902 and erected at Robinsonís Shaft. The engine is now in the care of the National Trust. © Barry Gamble.

Most surviving engine houses are rectangular in plan with a much thicker wall in the front (the bob wall), this was constructed using more massive stone (often cut granite) and was perhaps two-thirds of the height of the other walls. This wall supported the reciprocating beam (known in Cornish mining as a bob) which transmitted the reciprocating motion of the piston to the pump rods in the adjacent shaft (in the case of a pumping engine) or to the hoisting or crushing machinery. This wall had to withstand both the weight (that might be over 50 tonnes for a large pumping engine) and the rocking forces of the bob.
Carnon Stream Mine (1823, Listed Grade II). The remains of this creek-side engine house mark the unique Carnon Stream Mine that worked tin gravels in the river bed from shafts sunk within artificial islands out in the river itself. © Barry Gamble. Basset & Grylls Mine (also known as Porkellis United). The pumping engine house at Tyackeís Shaft was built following the tragic flooding of an older section of the mine when water and fine-grained tin Ďslimesí collapsed into the workings. © Barry Gamble. Botallack Mine, Crowns engine houses (lower pumping house 1835, higher whim house 1862, Listed Grade II). © Barry Gamble. Wheal Kitty, Sarahís Shaft (1910, Listed Grade II) © Barry Gamble.

The other walls braced the bob wall and helped to take some of the working stresses of the engine. The rear wall (usually with a gable that supported a pitched roof) contained the cylinder opening through which the cylinder, bob, and other large components were brought into the house. There were usually three chambers internally.

Associated structures include: boiler houses which were often attached to the engine house as a lean-to building; chimney stacks which were either built-in to a rear corner of the engine house or sometimes detached and connected by a flue; and engine ponds (usually upslope) which stored water for the engine condensers.

Simplified layout of a Cornish pumping engine house showing the position of principal components © HES.