• Home > Group Documentation > Journal > June 2006 > New dig at star shaft

by Alan Gray

Cavers involved - Mark Ireland, Alan Gray, Simon Fowler, Doug Harris, and Chris Binding (Cheddar Caving Club).

Historical Background

As a result of a severe and prolonged depression of Cornish mining in the 1860's, mine after mine closed and the second hand market was awash with beam engines and mining equipment. The Cornish miners looked further afield for work and came to the Shipham area during the 1840's and also from 1869 to 1872. During this second period of activity the Cornish miners were employed by a company, Messrs Vivian and Sons of Swansea, who were largely engaged in the smelting of calamine for zinc. They were also mining for Lead, Calamine, Iron, Manganese, Ochre, and other metals and minerals. The Company was managed by Richard White Rickard who lived in Cheddar at the time.

The traditional Mendip mine is entered via a narrow shaft and the ore and the majority of the waste has to be hauled up it. The Cornish miners opened up these shafts by enlarging the entrance to 6 feet by 8 feet and ginging the walls for quite a depth. They also employed pumping techniques to remove water below the watertable and thus increase the depth to which the mines could be driven.

Star Shaft was re-discovered in 2002 by a farmer who was driving his tractor in the field when part of the capping disappeared. The Wessex Cave Club explored Star Shaft; the first pitch is 25m deep which leads to a 30m long horizontal passage which terminates at the second pitch 20m, leading to the second horizontal passage 80m long which is for the majority of the year flooded. The entrance shaft was fenced off and temporarily capped to prevent animals or people falling in.

ACG Investigates

It was known that a steam engine was buried by or in the shaft at Rowberrow Shaft (another mine in Shipham reworked by the Cornish miners now covered with builder's rubble and the ground levelled off). Mark had an idea that a stationary engine may still be buried close to Star Shaft and wanted to find out if all the Cornish Mines in Shipham were similar, where the engine was buried next to a shaft, or in it, or was  this just peculiar to Rowberrow Shaft.

With a little persuasion a digging team was assembled and after just eight visits a walled pit (3.2m deep) and other foundations were uncovered (Figures 1 and 2). After comparing the size, shape and depth of these foundations against plans for a typical Cornish Beam Engine (Figure 3) it was established that the foundations were for such an engine - the first to be rediscovered on Mendip.

Historical Investigations

As part of his wider investigations concerning mining in the Shipham area Mark found an article in the Bristol Times and Mirror dated 24 August 1872 (page 4) relating to the sale of Mining Materials at Star -

My conclusion is that the Beam Engine was removed at an earlier date than the auction. It is also evident that the office for the mine, and also the mine, was quite close to the Star Inn; and as well as an office it would have been living accommodation for the mine manager. It would be useful to look up in the 1871 Census as there would be information relating to where the house was and who lived there. It seems probable that the house/office was rented or owned

by the mining company - if it was owned then there could be a separate auction notice for its sale in a newspaper around the date of 17 August 1872. Also the mining company owned all the furniture in the house. It seems possible that the mining firm did go bankrupt because they sold the theodolite - if the firm did wish to continue then I am sure this piece of essential equipment would have been retained.

Future Work at Star Shaft

In July 2006 Star Shaft will be concrete capped using funding from the CSCC. Access will be via a manhole cover in the centre of the cap.

From the listing of equipment to be sold at auction it appears that there was quite a large operation - extracting the ore (kibbles), processing the ore (jiggers and trommels), a smith's shop to repair and manufacture the tools and mining equipment, cisterns that would be used as staging tanks for removing the water from the depths of the mine. Apart from the beam engine one other item appears to be missing from this auction the stamps or crushers that were used to break up the rocks to retrieve the ore. Thus the auction refers to a large operation and more digging around Star Shaft will be required to locate the foundations of the buildings in which these processes were carried out and also the foundations for the engine house itself.

Behind the Cataract Pit are the foundations for the Cylinder, these will require digging out. Since the end of the beam would have been directly over the centre of the shaft and the pivot point is equidistant between the Hot Pit and Cataract Pit the length of beam can be calculated as 27½ feet (8.5m). Thus the centre of the Cylinder would be 5½ feet (1.7m) from the rear wall of the Cataract Pit.

With the farmer's permission we hope to cap both the Hot Pit and Cataract Pit and also provide a second entrance to Star Mine.

Glossary

CATARACT PIT (or cock pit) - A sub-floor area within the foundation levels of an engine house between the Cylinder Plat and the bob wall, containing the regulating apparatus, and giving access to cylinder hold-down bolts.

CONDENSER  - The cast-iron cylinder set in a tank of cold water immediately in front of the bob wall of an engine house in which the exhaust steam was condensed, creating a vacuum which greatly increased the efficiency of a steam engine. For a pumping engine this equipment was often contained within a pair of masonry walls projecting from the bob wall towards the shaft.

CYLINDER PLAT - The massive masonry base on which the cylinder of a Cornish Engine was bolted down.

EDUCTION PIPE - The large diameter pipe through which exhaust steam was drawn into the condenser set outside the bob wall.

ENGINE HOUSE - A building designed to contain steam, gas, oil or electric engines on a mine or other works. When forming part of the framework of a beam engine, these were particularly strongly constructed.

FLAT RODS - Reciprocating (or very occasionally rotative) iron rods used to transfer power from a steam-engine or water-wheel to a remote location

HOT WELL (Condensing Engines) - A receptacle for the hot water drawn from the condenser by the air pump. This water is returned to the boiler, being drawn from the hot well by the feed pump.

JIGGER - A large mechanically or hand-operated sieve set in a tank of water by which ore could be separated by waste. Sometimes constructed in groups within jigging houses.

KIBBLE - A large, strongly-constructed, egg-shaped, iron container used for ore and rock haulage in earlier shafts. Superseded by skips.

MITRE WHEEL - Used to transfer power from the stationary engine to other machines.

TROMMEL  - (from the Dutch word for drum, "trommel") is a screened cylinder used to separate materials by size - for example, separating different sizes of crushed stone.