 Prior to the use of matches, fires were sometimes lit using a burning glass (a lens) to focus the sun on tinder, a method that could only work on sunny days.Another more common method was igniting tinder with sparks produced by striking flint and steel, or by sharply increasing air pressure in a fire piston.Early work had been done by alchemist Hennig Brand, who discovered the flammable nature of phosphorus in 1669.