"Four minutes late," was all his comment, as she climbed in beside him. He started the engines and threw the helicopter screws into gear. The machine shot vertically into the air. Henry accelerated; the humming of the propeller shrilled from hornet to wasp, from wasp to mosquito; the speedometer showed that they were rising at the best part of two kilometres a minute. London diminished beneath them. The huge table-topped buildings were no more, in a few seconds, than a bed of geometrical mushrooms sprouting from the green of park and garden. In the midst of them, thin-stalked, a taller, slenderer fungus, the Charing-T Tower lifted towards the sky a disk of shining concrete.