as well as the branches of the river, and provided with locks for that purpose. These great waterways are free to all, and few of the results of British occupation are more appreciated in Egypt. Formerly all craft upon the Nile had to pay toll on passing under a bridge, which did nothing but hinder their progress, while those for whose convenience it was made passed without charge overhead. A Barrage, as its name implies, is designed to completely bar the bed of the river, so as to enable it to feed the canals at a higher level than would otherwise be the case, and also to allow the flood to pass through it easily. It needs, therefore, a very solid foundation from bank to bank, on which the arches which hold the movable sluice-gates can be securely planted. Its construction is, therefore, a very different and much more difficult matter than merely throwing a bridge over the stream, even a bridge with several spans. The difficulty is all the greater when, as here, the bed of the river offers nothing more substantial than shifting sands to build upon. It was for this reason that Linant wished to build the Barrages at leisure in the dry, and then divert the river from its old channels, and lead it through when they were completed. But Mougel chose to build his in the existing bed of the river, thereby increasing the difficulties of actual construction, though from other points of view there was much to be said for this plan. At the site of the Rosetta Barrage the bed of the river was not of uniform depth; he therefore filled up the deepest part of the channel, which lay on the right, with loose stones, so as to bring it up to the level of the bottom on the left-hand side. No cement was used in laying down this barrier, but the Nile mud filled the interstices and made it water-tight; when finished, this barrier was 60 metres wide and 10 deep at the deepest part. On this and on the natural sand he built a platform 46 metres in width and 3·5 metres thick, composed of concrete overlaid with brick and stonework. On the platform he raised his arches and piers, all built of brick. Each of the openings for the sluice-gates, sixty-one in number, was 5 metres wide. Like an iceberg, that part of the Barrage which is visible above water is much less than the invisible part below. To further strengthen the structure and keep it in its place, a mass of rubble pitching or loose stones was thrown into the river on the downstream side. This talus was 3 to 16 metres in depth, and at one part extended 50 metres downstream in a kind of tongue, narrowing down to 2 metres. The Damietta Barrage was built on a similar plan, but its downstream talus was not so large. Unfortunately, the concrete used for the platform was inferior, chiefly owing to the fact that Mehemet Ali, growing impatient at the slow progress of the work, ordered a certain amount of material to be laid down every day, and laid down it had to be in defiance of all engineering requirements.