In preindustrial times, when tunneling meant guys with a hammer and chisel, how difficult was tunneling through rock?* What kind of progress could be reasonably expected per day or per week? And were there practical limits to how far you could go before ventilation and other problems made it impossible?
*of course limestone would be one thing and granite another entirely.
ETA: I’m trying to establish a baseline for a RPG on what’s plausible, such as how quickly an underground fortress could be carved out of a mountain, or how long an escape tunnel could be.
I really hate to link to Wikipedia, but my primary source is offline and I do not feel like typing a lot. In any event, it’s an example of tunnel construction by an organized group of folks without explosives.
Even pre-gunpowder, it wasn’t just hammer & chisel - repeated heating & dowsing of rock was used to crack the tunnel face.
Agricola’s De Re Metallica is the definitive reference for medieval mining. Luckily, it’s online.
I think that translation is the greatest thing an American president has ever done before his presidency. Yes, that includes winning that little Revolution.