746 REPORT— 1888. 



TUESDAY, SEPTEMBER 11. 

 The following Papers were read : — 



1. Photographic and FhotozincograpMc Processes employed in the Ordnance 

 Survey. By Colonel J. H. Bolland, R.E. 



2, Note on Geographical Terminology.^ 5^ H. J. Mackinder, iJ/.J.. -J 



3. The River of Joseph, the Fayum and Raian Basins. 

 By Cope Whitehouse, M.A. 



The map exhibited (scale 1 in 50,000) is the result of surveys made during 

 1887-8, under the immediate direction of the Egyptian Government. In con- 

 formity with instructions drawn up hy Colonel Western, R.E., Director-General of 

 Works, Messrs. Lieurnur and Beychalier, of the Public Works Department, were 

 occupied from November, 1887, to Jlarch, 1888. The results are in entire con- 

 formity with the observations heretofore presented, and demonstrate the accuracy 

 of the sketch-map made by Captain Surtees, and the five previous lines of levels 

 run by Mr. Stadler and Major Shahin in the various expeditions of Mr. Cope 

 Whitehouse. The area of the Raian Basin at the contour of 30 metres (high Nile) 

 is G86 sq. Idiom., or about 180,000 acres. Its eastern extension — the Wadi Lulu — 

 is separated from the Gharaq Basin of the Fayum by a long narrow bank of hard 

 clay and soft conglomerate, covered with blackish sand, 1,000 to 2,000 metres in 

 width. Another small basin, the Wadi Safir, connects with the Gharaq basin at 

 level + 26 m., and the Raian Basin connects with the same depression at + 25 m. The 

 names of Lulu (the Pearl) and Sci/ir (the Sapphire) have been given to these basins, 

 in view of their future use as the gate, and preliminary reservoir, when the Wadi 

 Raian (irrigation) is tilled and utilised as an escape for the Nile Flood and an im- 

 pounding reservoir for the season of drought. The engineering details are stated 

 in the] paper in the Engineering Section, The similarity of shape with the Lake 

 Moeris of the Ptolemaic maps is more fuUy developed. The Wadi Muellah — a 

 depression in the desert to the S.E., about 30 kilometres long and 6 kilometres 

 wide — is separ&.ted from the Raian Basin by sandhills and rock, at a mean level of 

 50 m. A narrow strip, 8 kilometres long and \^ wide, lies about 5 metres below 

 high Nile. The southern extremity of the valley has no connection with the Nile 

 below + 100 m. It never, therefore, served as a channel for the Nile, but the dis- 

 tance is not sufficient to preclude a subterranean conduit. 



The survey of the Fayum has not been completed, but it is hoped that contours 

 will be run during the coming season around the north of the lake, and the exact 

 height of the various ruins determined. It is now beyond ca\'il or dispute that the 

 narrow passage at el-Lahun, with its dyke about 3 kilometres long and 10 metres 

 high, is the only channel of communication at the level of high Nile between the 

 great crevice which connects the watershed of Central Africa with the eastern 

 Mediterranean and these depressions. The area of the Fayum at this level may 

 be put at 2,500 square kilometres (1,000 square miles), and the Raian at 680 

 square kilometres (250 square miles) ; this surface of 3,180 square kilometres 

 (1,250 square miles) was one vast sheet of water before the dyke at el-Lahun was 

 established, not later than B.C. 1,400. The heavy alluvial deposits of the 

 Fayum prove that the communication was uninterrupted for a long period within 

 historic times. There are similar deposits in the AVadi Raian. Over 100 square 

 miles are 70 metres (200 ft.) below the level of the Mediterranean. The basins, 

 together or separately, are perfectly adapted to control the alternate flood and 

 drought. The Raian basin is, however, sufficient, and the Fayum appears to have 

 been fully reclaimed at a very early period, and again, in the Roman age, as it 



' Published in the Proceedings of the Royal GeograpMcal Society, Nov. 1888. 



