Depth shown in fathoms [vertical scale ca. 1:531,800]. Seafloor composition shown by shading and text. Major islands are shown. Operations in laying transoceanic telegraph cables (1865-69) shown in Sections I and II. From: The Journal of the Royal Geographical Society of London. Vol. 41 (1871), pp. 46-58; held in Firestone Library. Call number: G7 .J687.