Ms., mounted on cardboard. Relief shown by shading. Shows portion of Clarence Strait, based on descriptions from the steamship Nikolai I in 1839. With (on verso): Karta Baltiiskago Moria [Map of the Baltic Sea]. Signed by George Davidson,...
Inset: Treanguliatsiia na Gokhlandie. Shows triangulations around the Baltic Sea by various navigators. Longitude from Altona. From K. Zapis. Gid. Depar., Chast' 2, str. 223. With (on verso): Ploskaia karta chasti Proliva Diuka...