Dear Bingley: I had not noticed the shadow was that of the man standing before the Rumford. It does look rather small.
I wonder if it was intended for coal rather than wood.
I also think a Franklin stove would be more efficient, though taking up more room space.
Here is a URL with picture of Franklin stove, but regrettable does not show smoke pipe arrangement. Maybe like the Rumford it was originally incorparated into fireplace:
http://www.ushistory.org/franklin/pictures/