The word ‘oasis’ is old Egyptian, as also is the Arabic ‘wah,’ the latter word being also found in Coptic, and signifying an inhabited place; nevertheless, the word ‘wah’ was never used by the ancient Egyptians to designate the oases. These they called ‘otu,’ which means a place where bodies are embalmed. ‘Otu’ has its origin in the Theban myth, according to which Seth, the murderer of Osiris, was pursued by Horus to Koptos, where he was captured and thrown into a dungeon. His corpse was afterwards found by his friends, and taken to the oases for burial.[1] The inscriptions on the temple of Hibis in Kharga refer to the oases under the comprehensive name ‘Set-ament,’ the ‘Western Lands.’ About the same time Dr. Schweinfurth, whose services to Egypt in so many branches of science stand pre-eminent, published important contributions on some of the archæological remains. Two or three years later Brugsch Bey brought out an account of the antiquities of the oasis, with translations of a number of the inscriptions on the temples of Nadûra and Hibis. The antiquities will be briefly referred to in my account of the history of the oasis under the Persians and the Romans, and for fuller details the reader is referred to the publications of Cailliaud, Hoskins, Schweinfurth, Brugsch, and some still later writers. In 1893-94 Captain H. G. Lyons, R.E., in the course of a military patrol, undertaken in order to ascertain the measures necessary to protect the inhabitants of the oasis from possible Dervish raids, made valuable geological observations on the Eocene and Cretaceous systems, especially in relation to the connection of folding and water-supply. These he discussed in a paper read before the Geological Society of London in 1894, and it was mainly due to the interest it aroused, and to his initiative in pointing out to the Egyptian authorities the importance of having a comprehensive examination of the country carried out, that the Geological Survey of Egypt was established in 1896. The detailed survey of the Libyan Desert was taken up in October, 1897, and completed in June of the following year, the four oases being mapped on the scale of 1 to 50,000 by plane-table triangulation, checked and adjusted by numerous astronomical observations. Direct measurements by measuring-wheel were also employed to a considerable extent. Baharia Oasis was the first to be taken in hand, Mr. Leonard Gorringe and I taking the western side, and my colleagues, Messrs. Ball and Vuta, the eastern. This plan of splitting up an oasis-depression between two surveying parties was not, however, found satisfactory, and on the completion of Baharia it was decided that Ball should take up the oasis of Kharga, while Farafra and Dakhla fell to my lot. The results of this survey are published in the Memoirs of the Geological Survey of Egypt.