sentences:  He was a visiting artist-teacher at the Artist's Union in Helsinki, Slade School of Art at University College and Morley College both in London, and at the University of Wisconsin–Madison.Over the years, Thrall had solo and group shows at galleries in New York; the National Printmakers Show in Hilo Hawaii, Chicago, and more recently in Rockport, Massachusetts; in Door County, Wisconsin; New Visions Gallery at the Marshfield Clinic; and the Appleton Art Center's exhibition entitled "Symphony