The guides at Rhondda Heritage Park are former miners. Our guide is showing us two different lamps, both designed to burn without igniting methane gas that might be present in the mine. The hot gas coming off the flame is cooled by passing through the black metal mesh, so that it is too cool to ignite the methane in the mine. The lamp on the right lets more light out, since the light passes through clear glass instead of being partially blocked by the mesh. NEXT LIST