After his return to England in 1815, Davy began experimenting with lamps that could be used safely in coal mines. The Revd Dr Robert Gray of Bishopwearmouth in Sunderland, founder of the Society for Preventing Accidents in Coalmines, had written to Davy suggesting that he might use his 'extensive stores of chemical knowledge' to address the issue of mining explosions caused by firedamp, or methane mixed with oxygen, which was often ignited by the open flames of the lamps then used by miners. Incidents such as the Felling mine disaster of 1812 near Newcastle, in which 92 men were killed, not only caused great loss of life among miners but also meant that their widows and children had to be supported by the public purse. The Revd Gray and a fellow clergyman also working in a north-east mining area, the Revd John Hodgson of Jarrow, were keen that action should be taken to improve underground lighting and especially the lamps used by miners.