While critical mass of population seems to be an important part, I feel like there are a fair number of other things that have to be in place to make it more ec

While critical mass of population seems to be an important part, I feel like there are a fair number of other things that have to be in place to make it more economical to mine deeply. Then there's the next step Bret discusses: the Newcomen engine apparently worked well enough for mining purposes that the next big improvement took 50 years and then it was James Watt that got involved. "It is particularly remarkable here how much of these conditions are unique to Britain: it has to be coal, coal has to have massive economic demand (to create the demand for pumping water out of coal mines) and then there needs to be massive demand for spinning (so you need a huge textile export industry fueled both by domestic wool production and the cotton spoils of empire) and a device to manage the conversion of rotational energy into spun thread. I’ve left this bit out for space, but you also need a major incentive for the design of pressure-cylinders (which, in the event, was the demand for better siege cannon) because of how that dovetails with developing better cylinders for steam engines."