Powder mills ground ingredients for gunpowder & many grain mills were converted during the English civil war to prevent shortages.
Explosions were frequent and the mills often had weak roofs or walls which could easily be repaired in the event of a disaster.
The mill is shown here with an all wooden undershot wheel which could date back to much earlier times.Should the stream dry up or its level drop too low then the mill would not be able to operate.The corrugated roof would date from c.1820
Until the invention of corned gunpowder the individual ingredients would frequently separate in transit, this would weaken the powder considerably having been only roughly stirred in the barrel before loading the charge
Corned gunpowder is a method by which all the ingredients were ground together whilst wet & formed into cakes which were then reground when dry into the finished product