This is all I am going to tell you at present about the City and the East End, because it is quite impossible to tell everything. In the West End, too, there are many interesting things, and the most interesting of them must have chapters to themselves; for instance, the palaces belonging to the King, and the hospitals which are entirely for children. But there are other things which belong to the whole of London, and must be mentioned here. There is, for instance, the Embankment--rather a long word, but not a difficult one. It means the wall which was built for miles along beside the river to make a road and to prevent the river flooding right up to the houses. In old days, when people had their houses on the water's edge, when there came a high tide or a strong wind, the water washed up over them, and did a great deal of damage; so it was decided to build a strong wall beside the river, which the water, even in the highest tide, could not leap over. It was a wonderful piece of work. It is difficult to think of the number of cartloads of solid earth and stone that had to be put down into the water to make a firm foundation, and when that was done the wall had to be built on the top. But though the river had been banked up it could still make itself disagreeable. In 1928, driven by strong winds and high tides, after much rain, it flowed up over the Embankment in some places and broke through in others. It flooded many houses, and some people were drowned. The river also helps to cause fog; it seems as though it had gone to the smoke demon to find out what they could do to be spiteful, and they had agreed they could not do anything each by himself, but that together they could be very nasty. So every now and then the damp air which rises from the river, and the heavy smoke which comes out of the hundreds of chimneys, join together and make a thick black veil, and hang over London and come down into the streets so that people can't see where they are going, and when they breathe their noses and mouths are filled with nasty, dirty smuts. You who are London children know Mr. Fog-fiend very well. When you wake on a morning in November and find the room still dark, and are told it is time to get up when it looks like the middle of the night, then you know the fog has come; and he visits rich and poor alike. There is no keeping him in the East End.