This is a Georgian Ash Lancashire Ladderback Rocking Chair c1800-30.  This is a vernacular design from the Lancashire region.  Originally this was a normal chair but was converted not far after being made.  It is a classic design with turned and shaped front legs and straignt back legs.  It has straight spindles with a turned front spindle and the classically shaped back support rails.

it is

38 inches high

21 inches wide

20 inches deep