Unlike coal mines, Cornish tin and copper mines did not usually suffer from the dangers associated with the presence of explosive gases. Candles were therefore in use well into the 20th century, when they were replaced by acetylene gas and later electric lamps.
In the very early days of Cornish mining small, simple oil lamps were used, with the earliest being made of clay. By the 18th century, however, miners seeking a cheap and readily available source of light usually used tallow candles know as ‘dips’.
Tallow candles were made of animal fat – the best kind for candle-making was sheep fat. The candles were made by twisting threads of hemp or cotton together to make a wick, then dipping it repeatedly in the liquid fat to build up layers. Miners attached the candles to their hats, or walls near where they were working, using wet clay. They also used metal candle holders with spikes on the end so they could stick them into cracks in the rock.
The best kind of animal fat for making tallow candles was sheep fat.
Miners were careful to keep the wicks of their candles trimmed so they didn’t smoke too much or get too hot and make the fat melt too quickly. They could also use their candles to warn them about the quality of the air. Flames require slightly more oxygen than humans do to breathe, so if the candles would not stay alight, the miners knew to find a better ventilated area.
At the end of the 19th century paraffin (a by-product of petroleum refining) started to be used to make candles instead of tallow.
In 1815, Sir Humphry Davy (1778 – 1829) invented the safety lamp. It is commonly thought that, as he was Penzance born, he developed the lamp for use in Cornish mines – but its main purpose was to guard against disasters in coal mines (of which there were none in Cornwall), where dangerous amounts of explosive gases (known as firedamp) could build up and be ignited by naked flames. Davy’s safety lamp housed the flame inside a very fine wire mesh enclosure. He had discovered that while the mesh allowed enough air through to keep the flame alight, the flame could not propagate through it to ignite any firedamp present outside.
The safety lamp was not widely used in Cornish mines as it was heavy and not as bright as candles, but it was useful for testing for gas as the flame would burn higher and with a blue tinge in the presence of certain gases.
Carbide, or acetylene gas, lamps were developed in America at the turn of the 20th century. The acetylene gas was created by releasing water into a chamber filled with calcium carbide. The gas created by the reaction between them fed through a tube to a small burner tip, which was ignited. The size of the flame could be controlled by altering the flow of water and the brightness of the light was increased by a reflector surrounding the flame. The carbide lamp gave out much more light than a candle and burned for several hours on one charge of carbide.