Undershot POWDER MILL 

Powder mills ground ingredients for gunpowder and 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  original mill roof would  have been thatched but replaced with corrugated iron sheets in the years following the Napoleonic wars. Supplies of gunpowder continued to be in big demand in the following years with campaigns in Africa & Asia. Corrugated iron first appeared in  the 1820's.