One thing I’ll be mentioning in Part III, as I ran out of space in this one: Drebbel in the 1610s applied his insights into perpetual motion to invent a self-regulating oven/furnace. Using mercury rather than water to trap air in a tube, much like the inverted flask I described, rising temperatures would raise a float sitting on the mercury that would then close the aperture for the air feeding the oven’s flame.