and more saline, but the power might continue to be maintained for very many years before the lake became as rich in salt as the Dead Sea. But alas! an investigation of the northern borders of the depression showed that the hoped-for traces of a former connection with the Mediterranean Sea do not exist. The depression is entirely shut in from the north, either by great cliffs, or by ground lying so high that the cutting of a canal to the sea is utterly impracticable. Of the 56½ kilometres from the sea-level contour of the depression to the coast along a line running 12° east of north from Moghara Lake (which is the easiest line hitherto found for the cutting of a canal), only 16 kilometres are at less than 50 metres above sea; 31 kilometres lie at altitudes between 50 and 100 metres; and 9½ kilometres are above the 100-metre level. An open channel being thus put out of the question, it was next natural to inquire whether a tunnel, or a channel partly open and partly tunnelled, could be excavated to serve for the conveyance of sea-water into the depression. But even this, though perhaps not impracticable, would be a very costly undertaking. The conveyance of the requisite quantity of water, even at a relatively high velocity (which of course implies a considerable slope), would necessitate a tunnel or tunnels of very large dimensions. To convey 36 million cubic metres a day at a velocity of 5 kilometres per hour would require a sectional area of 300 square metres—_i.e._ if two tunnels were made, each would have to be 14 metres in diameter. The cost of boring and lining such tunnels would certainly be very great, and it is doubtful whether the value of the power generated could justify the capital expenditure involved in the excavation and other works which would be necessary. Until more is known of the nature of the strata through which the aqueduct would have to pass, and as to the length of tunnelling and amount of open cutting which would be required, it is impossible to form even an approximate estimate of the expense which the undertaking would involve. All that can be said at present is that the utilization of the Qattara Depression offers a possible means of obtaining power on a large scale for the drainage of the low-lying lands of the Delta, with at the same time a prospect of improving in some measure the agricultural resources of the Mediterranean Littoral; much further investigation will have to be accomplished before any judgment can be formed as to whether such a project would be an economically sound one.