Includes inset: Plan of the cave at Umm Nírán [scale ca. 1:1,370]. Bearing of cave entrance and course of underground water are shown. Western Trachon and Eastern Trachon (volcanic fields) are shown. Relief shown by hachures. Route of expedition shown in red. From: Journal of the Royal Geographical Society of London. Vol. 42 (1872), pp. 49-61; held in Firestone Library. Call number: G7 .J687 v.42 1872