In the winter of 1823-1824 Baharia was visited by _Pacho_ in company with F. Muller. In an account of Pacho’s travels[4] published after his unhappy death, there is no reference to his observations in this oasis beyond an indication of his route on the map. _Wilkinson_[5] visited the oasis of Baharia in 1825. The Rohlfs’ expedition of 1874,[6] with the distinguished scientists K. von Zittel and W. Jordan as geologist and topographer respectively, added very considerably to our knowledge of Baharia, more especially in the way of fixing precisely the geographical positions and levels of its principal points. Zittel, however, did not visit this oasis, and in consequence its geological structure was not studied, the few references to it made in the publications of the Rohlfs’ expedition being based on an examination of specimens collected by Ascherson. Probably the most accurate map hitherto existing of Baharia Oasis is that of _Ascherson_,[7] who spent nearly three months there in 1876. Ascherson, who entered the oasis by the road from the Fayum and returned to Samalut, chiefly directed his attention to botanical observations, but his memoir contains some valuable topographical and geological information which supplements that of previous and later observers in important measure; he has also the distinction of finding the stela of the reign of Thothmes III already referred to, and the remains of an Egyptian temple; the latter is probably identical with one of those discovered by Steindorff in 1900. The short memoir by _Capt. H. G. Lyons_, R.E.,[8] published in 1894, brought together a number of observations on the geology of the Libyan Desert generally, and his discovery of fossils, referred to _Exogyra Overwegi_, for the first time established the Upper Cretaceous age of the clays and sandstones forming the floor and lower part of the scarp in the northern end of the depression. In 1897 the Geological Survey carried out its examination, the results of which are set forth in the following chapters. Since the survey expedition, Baharia has been visited by Steindorff,[9] who during his five days’ stay in the oasis made important additions to our knowledge of its antiquities. These will be further referred to in the chapter on the topography of the oasis. * * * * * [Footnote 1: This ruin was described by CAILLIAUD (_Voyage à Méroé. etc._, vol. I, p. 183) who records that in his time (1820) only the central arcade remained standing. Steindorff found in 1900 that even this last fragment had fallen.] [Footnote 2: _Narrative of the Operations and Recent Discoveries within the Pyramids, Tombs, and Excavations in Egypt and Nubia, and of a Journey to the Coast of the Red Sea, in search of the Ancient Berenice, and another to the oasis of Jupiter Ammon._—London, 1820, pp. 395-433.]