The brand below the seat “S. GIBBS R.I.” is likely to be an original brand of ownership.  (The Gibbs family is a known family in Newport of the time, and furniture was often branded by the original owner.)  

The seat is pine, and
there are three old drain holes in the seat, which were put there originally,
as others have been found with such holes, (we assume the cabinetmaker added
this feature to make the chair usable indoors or on a porch).  This chair obviously was not used outdoors,
given its condition and original paint.  The feet are slightly reduced
through normal wear and there are no other breaks or alterations whatsoever.
The paint is it’s original old green paint and all is in as-found condition.

This chair is listed in the Yale University Art Gallery’s Rhode Island Furniture Archive, which states that this was the property of Duncan A. Hazard (1874–1939) of Newport, Rhode Island consigned by his estate
to Parke-Bernet Galleries, New York, November 9, 1940, lot 128.
http://rifa.art.yale.edu/detail.htm?id=137699&type=0

This chair is related to the chair illustrated by Charles Santore in Windsor Style in America (cat.

no.35), made for the Redwood Library and Atheneum in Rhode Island. 
Another strikingly similar low-back Windsor (which is also stamped S.
GIbbs) is in the collection of the Redwood Library & Anthenaeum (see
scanned image below).

Height: 28 in.  Seat Height: 15 in.  Width: 27 1/2 in. Depth: 15 in.