This is the “Rising Sun” armchair. It was the chair that George Washington used during several months of sessions of the Constitutional Convention. It is made of mahogony wood and measures around 60.4″ high x 30.5″ wide x 22.9″ deep. For source and more details, click here.
Images from: http://www.cr.nps.gov/museum/exhibits/revwar/image_gal/indeimg/armchair.html