A General Chart of The North Sea Constructed from a Great Variety of Original and Accurate Surveys by John Purdy

Scale: circa 1:1,800,000 (Lat). Blue-backed chart on two sheets joined. Canvas edged. Four insets, sixteen views and drawings of Bell Rock lighthouse in a gale Insets: 1. (Pentland Frith) circa 1:200,000 (bar); 2. Sound of Balta circa 1:53,000 (bar); 3. The Environs of Bergen circa 1:225,000 (bar); 4. Christian Sound & Co. circa 1:250,000 (bar)