Safety fuse

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 waterproofed 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).

Documentary evidence suggests that the earliest fuses were first used by the Chinese between the 10th and 12th centuries. After the Chinese had invented gunpowder, they began adapting its explosive properties for use in military technology. By 1044 they were using gunpowder in simple grenades, bombs, and flamethrowers. Gunpowder did not reach Europe until the early 13th century, carried over from China by European traders and merchants along the old Silk Road.

For three centuries gunpowder was primarily used for military warfare. It was not until 1574 that gunpowder was first introduced to the mining industry, and it took until 1617 before it was first used in a large-scale mining operation—at Thillot in France.

One of the problems miners faced when introducing gunpowder into their operations was that it was relative easy to ignite when exposed to sparks, intense heat, or flames. The method used by miners to blast away rock involved drilling several holes across a rock face which would be filled with charges of gunpowder. In order to confine the gases produced on ignition, the gunpowder was confined within each shot hole by inserting a pointed rod known as a "needle" in the gunpowder-charged hole and then packing in soft clay and tamping it down to form a plug. The "needle" was then removed and replaced by a fuse. To prevent sparking, a copper needle and a non-metallic ramming rod, typically made from hickory, were used.

If a spark was created the results could be disastrous to the work force, and this was a common occurrence. Miners and mine owners were aware of the dangers of the use of gunpowder in mining, as is evident in their instructions for handling the material. A mill in England preparing the material wrote in its instructions, "Whosoever is at Labour within or without the powder magazines should execute his commission in such a respectful and revered silence as is seemly in such a place where (unless the Almighty in his Grace keeps a protective hand over the Labour) the least lack of care may not alone cause the loss of life of all present, but may even in a moment transform this place as well as its surroundings into a heap of stone."

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