CombatWombat51 said:
1. What was coal used for before steam power? Was it heavily mined?
You are going to have to be careful about this, because a lot of what was called 'coal' in early records was charcoal (made by charring wood), not mineral coal. For example, when you read about a saint being martyred by burning 'over coals', they mean that he was barbecued over the coals of a wood fire, not that he was burned in a coal fire. And when you read of somebody being tortured with hot coals, those coals will be burning embers taken from among the coals of a wood or charcoal fire. If you come across a reference to Egyptians, Greeks, or Romans using 'coal', be sure that it mentions that they mined it, because maybe "carbo" has been translated as "coal" where "charcoal" or even "ember" would have been better. Consult decent dictionary, and you will see that the primary sense of the word 'coal' is "a piece of glowing carbon or charred wood: ember", the secondary sense is "charcoal", and the usual modern sense is only tertiary. This sort of thing misleads the people who compile translating dictionaries.
Marco Polo describes mineral coal as one of the wonders of his stay in China: a black stone that burns better than wood etc. So evidently it was unfamiliar in Venice in his time.
But by the Late Middle Ages (
Wikipedia says 'after about 1000 AD') "sea coal" as distinct from "char coal" was an article of commerce in England and Scotland (and probably other northern countries that I don't know of). It was mostly burned in fireplaces to heat rooms, because food cooked over an open coal fire picks up an unpleasant taste (and traces of some pretty nasty organic poisons), and coal as such is of little use in metallurgy. Metallurgists and smiths invariably used charcoal in their industry, not coal, at least until coke (which you can think of ascharcoal made out of coal rather than wood) was invented in the 17th Century. If you come across any reference to 'coal' used in making steel, there is something wrong (probably mistranslation, or else somebody believing a dictionary that tells him that the result of charring wood is called 'coal' in English).
Coal was mined on [what we would now call] a small scale in the North of England in late mediaeval times, and shipped south in specially-built coaling ships.
As for Tilla the Hun's "Mechanus", you will search in vain. He seems to be thinking of the aeropile, which was invented (along with a number of other amazing tricks such as the first known coin-fed vending machine) by
Hero of Alexandria. (Also sometimes transliterated as 'Heron' rather than 'Hero'.) Many of Hero's gadgets were powered by the heat of fires, but those could easily have been wood or charcoal fires. If you find a source that seems to say that they used coal fires, be careful about the translations. Make sure that the original source mentions mining or a burning stone.
