19th-century tin mine, Cornwall. Artwork of miners and walkways at the Botallack Copper and Tin Mine at St Just, Cornwall, England. This mine, under various names, dates back to 1721. Undersea excavations were reported from 1778, and this artwork illustrates the situation in around 1862. The workings extended out under the sea for nearly a whole kilometre, and some of the tunnels were only a few metres below the seabed. In 1863 the mine employed nearly 300 men, over 100 women, and over 100 boys. The mine had reached a depth of 400 metres. The fortunes of the mine fluctuated over the years, and eventually it closed in 1914. During its history, it produced thousands of tons of tin and copper. Artwork from Mines and Miners (L. Simonin, 1868).