I was just trying to remember the name for the pot that works the same way. Sometimes they are used to make Chinese or Mongolian Hot Pot meals.
This is the pot with a fire in the middle just like a Kelly kettle.
Again it is fuel efficient, but awkward to pack.
http://www.wokshop.com/HTML/products/steamers/steam_hp_chinese_brass.html
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May set off to explore without any sense of direction or how to return.