“Tom gazed down at the tiny forms of Londoners clambering over the new city, laying cables, welding girders, marking out the shapes of streets and buildings on the bare deckplates. “But it’s got no wheels,” Wren pointed out. “I can see you don’t know what Mag-Lev stands for, my dear,” said Dr. Childermass. “It’s a code name, isn’t it?” asked Tom, who didn’t know, either. “Oh no,” Dr. Childermass said. “Mag-Lev is just a shorter way of saying Magnetic Levitation.” “It floats!” said Wolf, gazing down at the new city entranced. “Like a gigantic hovercraft …”