Steel mill formerly used with a flint by the colliers of N. England to give light in places subject to fire-damp, pre 1865

This is a device that was used for giving light in fiery mines before the invention of the safety lamp. It was thought that the spark from a flint and steel would not ignite fire-damp; but, although such sparks are less dangerous than a naked light it was found that under certain circumstances they would cause an explosion, and these mills quickly disappeared upon the introduction of the safety lamp. The mill shown consists of a steel disc 5.5 in. diam. driven through spur gearing at five times the speed of the winch handle, which was rotated by a boy who held a flint against the revolving disc and so produced a stream of sparks. These mills were also made for clamping on to the forearm, and probably supported their own flint.