Wheal Maid Lode. Underlies S. to the 30 fm. level, after which it underlies N. 13 degree. The total depth was 190 fathoms.
By 1779, Wheal Virgin, West Wheal Virgin, Wheal Maid and Carharrack Mine were being worked by seven Newcomen engines.
Letter from James Watt 24 April 1787 Addressed to: Mr Thomas Wilson, Chacewater, Truro, Cornwall, Via Bristol
We did not answer your last about the undertaking Wheal Maid Engine because we do not well know what they or you call the Engine, that is to say whether you mean to include pumps & pitwork & the wages of Idle Captains & labourers who in fact have nothing to do at the Engine however you may form a very good judgement of it cost from Poldice No5 encreasing the expence as the squares of their diameters, say nearly at 34 to 40. I am like you anxious to hear how Poldice Great Engine performs, there is too much risqued in such an attempt & after all it is probable two Engines would have been as cheap, and if Wheal Maid costs no more than 2, 63s it will not be too dear & that is the short argument, with these illiberal Captains.
October 1785, Matthew Boulton to John Wilkinson
"We have now undertaken to make an Engine for Wheal Maid to work an 18 box to the depth of 160 fathoms or 110 fat. Below adit. This is to do the work of 3 Engines and thereby make a great saving."
5. Letter. Thomas Wilson (Chacewater) to Boulton & Watt (Soho). 7 Mar.
“Wheal Maid pumps. Refusal of United Mines to execute the agreeement till the engine was at work.”
The profits from 1800 to 1840 are said to have reached £200,000.
1819 Wheal Maid was sunk 130 fathoms below the adit.
Between 1820 and 1852 Wheal Maid and Carharrack yielded 23, 552 tons of ore containing 1,542 tons of copper.
1852 Wheal Maid was amalgamated with Carharrack Mine and Poldice and worked as St Day United.
1983, the Carnon Consolidated Tin Mines Ltd. started to explore the Wheal Maid workings. An adit was driven, cutting three mineralized veins on a distance of 655 m. In 1984, this adit - declining to the southeast - was further driven ahead to connect this section to the Wheal Jane workings. In a depth of roughly 100 m, some levels of the old 'Whiteworks section' were cut, from where a number of interesting minerals was recovered. Ref.: Lapis 11(2), 38 (1986). 1985 Ref.: Mining Annual Review (1985): 485. A tin mine owned by Carnon Consolidated, Ltd., a subsidiary of Rio Tinto Zinc. Started about 1985. 1984 operations produced an estimated 35,000 tons of ore (230 tons Sn). Depth is 655 meters.
2002. The offer by Gwennap Parish Council to buy the site of the Wheal Maid site for £1 has been accepted by the owners Carnon Enterprises.
Gwennap Area Mines.