Safety lamp it. Air is drawn in and descends just inside the glass, passing up through the flame in the centre of the lamp. The outer casings of lamps have been made of brass or tinned steel. If a lamp bangs against a hard piece of rock a spark could be generated if iron or untinned steel were employed. Within months of Clanny's demonstration of his first lamp, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. Subsequently, Clanny incorporated aspects of both lamps and produced
Mercury-vapor lamp arc lamps operated in a mixture of air and mercury vapor at atmospheric pressure for lighting. The German physicist Leo Arons (1860–1919) studied mercury discharges in 1892 and developed a lamp based on a mercury arc. In February 1896 Herbert John Dowsing and H. S. Keating of England patented a mercury vapour lamp, considered by some to be the first true mercury vapour lamp. The first mercury vapor lamp to achieve widespread success was invented in 1901 by American engineer Peter Cooper Hewitt. Hewitt was issued on September 17, 1901. In 1903, Hewitt created an improved version that possessed higher