Before gunpowder was applied to civil engineering, there were two ways to break up large rocks, by hard labor or by heating with large fires followed by rapid quenching. The earliest record for the use of gunpowder in mines comes from Hungary in 1627. It was introduced to Britain in 1638 by German miners, after which records are numerous. Until the invention of the safety fuse by William Bickford in 1831, the practice was extremely dangerous. Another reason for danger were the dense fumes given off and the risk of igniting flammable gas when used in coal mines.