"I told you she was geared to high!!". To cook small portions of food and particularly to make a brew, prisoners of war constructed blowers from metal tins and other scraps. Over the years these evolved into enormously efficient and powerful devices that could be geared to a level where they neared furnace temperatures. 

 

This illustration is taken from "Handle With Care" by R. Anderson and D. Westmacott, a book of sketches made by Prisoners of War.