CISMAS

The Wherry Mine

One of the most unusual mines in Cornwall and an early tourist attraction, the ‘famous’ Wherry Mine, is still well-known today – although there is little to see without getting very wet feet. The mineshaft was (and still is) out in the sea, on the western edge of the Wherrytown Rocks, Penzance.


Mining probably began there soon after 1700, but it was not until 1778 that the real story starts. That is when Thomas Curtis –usually described as  a ‘poor miner’ - decided there was money to be made at the Wherry.  He sunk a shaft on the intertidal reef, and protected it with a ‘caisson’ – a tall, chimney-like wooden structure. This was joined to the shaft on the seabed, and extending above the high tide level - where a winch platform was built above it.

 

Wherry Mine 1793

A drawing showing the Wherry mine sometime between 1793 when the first steam engine was installed, and 1796 when the old shaft was damaged in a storm and abandoned. The engine house seems to be a wooden building   

 

At first the pumps were operated manually by the miners on the winch platform above the caisson, and access to this was by boat from the shore - but later a bridge, apparently over 200m long, was constructed. This provided access between the platform above the caisson and shaft, and from 1793 a steam engine, housed in a shoreline engine house, operated the pumps in the shaft. The power was transmitted by flat rods carried on the bridge.

It seems that Thomas Curtis had been right: the mine was widely thought to be very rich and to have made large sums of money for its investors. In 1795 there were 90 men employed there, working in shifts day and night.

Wherry Mine Old Shft

A panorama constructed from several photographs showing the iron pipe and the cut in the rock which may be the site of old shaft

 

In January 1796, a storm destroyed the caisson and flooded the mine, which by that time had reached a depth of about 20 fathoms (36m). In order to ensure that profitable working could continue, a new shaft was started about 80m nearer to the shore. The plan seems to have been to sink the new shaft to a depth of 24 fathoms (43m), and then to drive a level out to the lode at a point below the old flooded workings. We do not know whether this attempt met with any success; what we do know is that two years later in 1798 the mine ceased working. Local legend attributes this to an American ship breaking loose from its moorings and damaging the infrastructure -  although there is little evidence that this ever happened, and none to suggest that it was a crucial factor in the closure.

Wherry Mine New Shaft

An aerial view of the timber lined new shaft after weed clearance. This was taken 21st February 2019 with a tide height of 0.3m above chart datum. The ranging poles are 2m long.

 

In 1836 a new company was set up to work the Wherry Mine again. New investors were eagerly sought, and their money used to fund a new engine house, steam engine and bridge. Once again, a waterproof caisson was constructed, presumably on the site of the new shaft begun in 1796. But in fact, this phase of working the mine was short-lived.


In around 1838 - after £9600 had been ‘called up’ from the hapless investors – work at the Wherry was once more stopped. The investors (referred to at the time as ‘wherry [very] foolish,’ and widely dismissed locally as credulous Londoners) had spent £9600 -  over one million pounds in today’s money. In 1840 the engine house was dismantled, the machinery and pitwork of the mine auctioned off, and the granite used for a row of cottages that survived until the mid-20th century.

 

 

Wherry Mine Post

The rectangular rock cut socket  with the circular wooden post P6  still in place. The post is 0.35m (13.7 inches) in diameter.

Timber Post P9

Timber post P9, 0.29m (11.4 inches) in diameter. The exposed upper surface of the post exhibited a number of small, tightly-spaced holes – indicative of attack by wood boring molluscs such as the ‘gribble worm’

 

CISMAS began survey work at the Wherry Mine in March 2018. We have found the remains of the ‘new’ shaft (dug in 1796), the infilled remains of old shaft (abandoned in 1796), and 19 of the timber supports for the 1836 bridge from the engine house to the shaft.


Want to know more? You can download the report of our discoveries here.

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CISMAS