Examine the manner in which the pieces of the chair are joined together. Windsors are "stick built" chairs. The various pieces of a Windsor are turned on a lathe and have round tenons that fit neatly into round sockets. A Windsor chair will not have any "squared " joints.
Consider the legs of the chair. Windsor bowbacks have legs that are widely splayed and run from the seat to the floor. Traditionally the legs are approximately 17.5 inches long.
Examine the chair back. The back of a Windsor bowback has a sharply bowed shape with the outermost piece running up from the left side of the chair looping 180 degrees and returning to the seat on the right side of the chair. Between the left and right side are a number of spindles that run from the bow to the seat.
Examine the chair seat. The back of the chair should connect to the seat of the chair only. The same is true of the legs. At no point should the chair back and legs connect directly to one another.
Determine the variety of wood used in the construction. Windsor bowbacks were almost never made from fancy wood such as mahogany or walnut. Less-expensive woods were normally used. Certain woods have structural qualities that lend themselves to making bowbacks. Among these are oak, hickory and ash because they are strong and easily bent into shape. Birch, maple, pine and poplar were also commonly used. Often more than one type of wood was used on a chair. Later the chair would be painted to make the appearance uniform.