Coal And Dead Fish
c2000 BC
-2000 -2000
00.00W51.30N
NAT

LONDON, ENGLAND
	Sometimes we think of the smog over our cities as a modern problem, but it isn't.  In fact, at the end of the 17th Century the burning of coal was so widespread that a thick, black cloud hung over the city of London.
	The world's coal was formed when ancient plants were compressed under the great weight of tons of earth and stone.  The harder they were compressed, the better the coal, ranging from the soft brownish lignite to the better bituminous coal, to the top-grade, hard, black anthracite.
	Mining coal in the early days was a dangerous enterprise. Miners sometimes used candles, but the flame could cause the mine gases to explode, so they began using dead fish, which glow in the dark.  But the light wasn't very bright and, as you might guess, the miners didn't much care for the odor.
	Mine safety greatly improved in 1815 when the Englishman Sir Humphrey Davy invented the safety lamp.
	Though coal is still used as an energy source throughout the world, oil has replaced it in many cases because it is easier to use.
