London Main Drainage: constructing the invert for the southern high-level sewer, 1861. The northern outfall sewer is about five miles long....The remarkable manner in which the embankment or bed is formed upon which the tunnels are to be built will be best understood by reference to our Illustration. The whole of the upper soil is first excavated, then a solid embankment of concrete is formed. In some places this embankment is as much as twenty feet in depth and one hundred feet in width. It is formed by carrying out a staging upon which several lines of rails are laid. The concrete is made of the best Portland cement, and is mixed at a regular concrete manufactory...from there it is conveyed in trains of waggons drawn by locomotives to the tip or head of the bank, where it is pitched from the staging to the required level below. The upper surface of this concrete is prepared to a proper shape to receive the inverts of the three tunnels. This extraordinary bank was necessary on account of the treacherous nature of the soil upon which the drains were to be placed. It will be a magnificent work when finished, and one that may almost endure for ever. From "Illustrated London News", 1861.