This is an 18th century wine tester. The small glass balls, each slightly different, would be floated on the surface of wine. Based on how they floated, it could help one determine the wine’s density. This set is made of wood, glass, and paper, and measures around 1.5″ x 9.25″. For source and more details, click here.
Image from: http://www.cr.nps.gov/museum/exhibits/revwar/image_gal/morrimg/winetester.html