Certain arches in the Damietta Barrage were selected, and in them five-inch holes were bored right down through pier and platform alike. When the bore-holes were complete, they were lined with iron tubes. Clay was then forced through the tube by means of an iron rammer, and as much as could be made to spread out at the bottom of the hole was put in and rammed. As far as the clay went, the experiment was not an entire success; but the boring brought to light a condition of things in the very vitals of the Barrage which demanded drastic treatment, for the bore-holes proved the existence of large cavities in the original platform, and in some places there was free water communication between one bore-hole and another. Some piers in the Rosetta Barrage were therefore chosen for a similar experiment, but this time liquid Portland cement was used instead of clay, and the results were entirely satisfactory. Few discoveries have been of more signal service than the invention of Portland cement. It is not too much to say that it has revolutionized hydraulic engineering by the facilities it affords for constructing solid works in water. Its strength and resisting power is enormous, but its greatest quality is that it hardens and solidifies under the action of water, and, so far as is known, only goes on getting harder and harder with time. The borings in the Rosetta Barrage having revealed similar deficiencies to those in the Damietta, it was decided to apply to both a thorough dose of this invaluable and invigorating medicine. In 1897 five holes were bored in each pier of the Rosetta Barrage (their united length amounted to very nearly 6 kilometres), and into each was poured a quantity of liquid cement. The necessity for the treatment was proved by the fact that in some cases the cement travelled right through from the bore-hole in one pier and rose through the bore-hole in an adjoining pier till it reached the top. One pier actually swallowed 439 barrels of cement, while its neighbour took a lesser but still gigantic draught of 327 barrels. There was no doubt that the cement thoroughly explored and filled all the cavities existing in the foundations under the bridge. In all, 3,254 barrels were used in the Rosetta Barrage alone. In 1898 the grouting process, as it is called, was applied with equal success to the Damietta Barrage. To use Sir Hanbury Brown’s homely but expressive image, the process applied to the Barrage was exactly that followed by a cook who wishes to finish off a cold pie with its proper complement of jelly. The jelly is introduced into the pie in the form of warm gravy, which penetrates into and fills every recess of the succulent interior, and then solidifies as it cools.