The safety fuse is a type of fuse invented and patented by William Bickford in 1831. Originally it consisted of a "tube" of gunpowder surrounded by a water-proofed varnished jute "rope". It replaced earlier and less reliable methods of igniting gunpowder blasting charges which had caused many injuries and deaths in the mining industry. The safety fuse burnt at a rate of typically about 30 seconds per foot (1 second per cm).