This is a Denney Improved Ericsson (Hot Air) Engine from around 1900.  I've never seen one before,
and amazingly, there were THREE here at this show.  This engine came with different firebox options
depending on your fuel.   This one is burning corn cobs.  Running at about 100 RPM, it was used to pump
water from a 130' deep well.  This is a VERY nice display, with lots of  "monkey motion" from the engine.