He began his Saharan expeditions in 1865, and named the great expanse of dunes the Große Sandmeer, but it was not until 1924 with the maps of Ahmed Hassanein that the full scope of the Great Sand Sea was appreciated by Europeans.
Han begyndte sin Saharaekspedition i 1865, og kaldte det store område med sandklitter for Große Sandmeer, men det var først i 1924 med kortene tegnet af Ahmed Hassanein at det fulde omfang af det store sandhav blev kendt af europæere.