"Beneath the pavements and streets of London runs a veritable network of pipes and cables that play their part in helping to maintain the social services. The sectional view seen above gives a clear idea of the maze of tubes, tunnels and piping with which the capital is honeycombed and which compromises the most extensive service in the world.
"Included in this marvellous underground system are a 4,500,000 miles of telephone and telegraph lines and more than 45,000 miles of pipes and mains. Gas mains measure 12,000 miles, the water-pipes of the Metropolitan Water Board are 8,000 miles in length and there are 25,000 miles of smaller pipes"
"In the bottom right-hand corner is a sectional view of the new conduit method gradually being extended beneath Lodnon's streets"
Source: "Modern Wonder", Vo. 2., #29 (1937)