The study of the possibilities of Lake Tsana as a reservoir for the Blue Nile, originally reported on by Mr. C. E. Dupuis in 1903, has been continued by expeditions visiting the lake under Mr. A. B. Buckley in 1916-17, and under Mr. G. W. Grabham in 1920-21. The results of these studies were published by the Egyptian Government and the Report of the Mission to Lake Tsana in 1920-21 by Messrs. G. W. Grabham and R. P. Black is particularly full and interesting. All reports agree in emphasising the extreme suitability of Lake Tsana for conversion into a reservoir of a capacity of between 3,00o and 4,000 million cu. metres. The political questions arising from the gradual con version of the Nile from a natural river into an artificially regu lated stream, whose flow is controlled by reservoirs at various points on its course in several different countries, have begun to make themselves felt, and a comprehensive solution of the result ing difficulties has yet to be found.
From the point of view of navigation and trade no new developments have taken place on the Nile in recent years. The river remains a most useful high
way for local traffic in the various sections into which its length of 4,00o m. is divided by the occurrence of falls and rapids ; but the nature of these breaks is such that the development of through traffic on any scale is never likely to be economically possible. There are considerable possibilities for the development of water power on the Nile especially at the Ripon and Murchison falls in Uganda; and the utilization of the large amount of power run ning to waste at the Assuan dam has been repeatedly considered and discussed; but the localities in which these opportunities occur are remote, and no useful application of them to practical pur poses has yet been devised ; in the case of Assuan the inter mittent character of the power obtainable, which though very large when the reservoir is full in the early part of the year is prac tically nil during the flood season, has hitherto proved an insur mountable objection to economic utilization. (C. E. D.)