View this artwork by appointment, at Tate Britain's Prints and Drawings Rooms
These sketches appear to be distant views Stettin Harbour. The artist has inscribed ‘Daff’ and ‘Volin’ at rear, which probably refers to ‘Haff’ (i.e. ‘Stettiner Haff’, the German for ‘Stettin Harbour’) and ‘Wolin’ (i.e. the island of Wolin in the Baltic Sea).