In regard to the cartographic material, most of which is new, special attention has been given to the place-names, and it is believed that these are correct in almost every case. But as the names are in languages not understood by European draughtsmen, it is almost impossible that mistakes have been entirely avoided; in any case where map and text may disagree in spelling (the differences will, I trust, never be so great as to leave doubts of identity), the text should be followed in preference to the map, as mistakes in the text are usually more easily perceived and corrected. I would remark that although the whole of the field maps have been employed in preparing the small scale ones, yet the full detail can be recorded only on the large scale maps, which are given for the most important districts; a future explorer would do well, therefore, to refer to the manuscript field maps which are filed at the Survey Office at Gîza, before concluding that no more detailed survey exists than is shown on the maps in this book. The plates illustrating the scenic types are from my own photographs, while those illustrating the natural-size aspect of the typical rocks are reproductions from water-colour drawings which I made from actual specimens. These coloured plates of rocks are mainly designed to enable prospectors to identify readily the ordinary kinds of stone they meet with in the field; but they will also serve to give to petrologists an idea of the appearance of hand specimens of rocks from this part of the world, which are not frequently met with in the great museums. The text figures of rock sections I have mostly drawn at the microscope on silver prints from photographic plates, the prints being afterwards bleached out with mercuric chloride; they will appear slightly diagrammatic in places, owing to the necessity of using lines and dots for tints, but I find I myself get a better idea of a rock from a drawing of this kind than from a photograph. Much detailed surveying of this mountainous and arid region remains yet to be done, especially in the districts round the heads of the Wadi Alaqi, before our knowledge of it can be considered complete. It is hoped, however, that a substantial beginning has been made towards this end, and that future work may be facilitated by the observational data recorded in the following pages. JOHN BALL. CONTENTS. * * * * * PAGE. CHAPTER I. — Introduction 1 „ II. — General Description of South-Eastern Egypt 18 „ III. — Surveying Methods and Principal Geographical Results 39 „ IV. — The Wadis draining Westwards to the Nile 78