At a word from him the driver touched a concealed spring and an aperture appeared beneath the control-lever, of which I have spoken in a preceding chapter.

Within was a small cube of black crystal, through whose sides I saw, dimly, a rapidly revolving, glowing ball, not more than two inches in diameter.
Beneath the cube was a curiously shaped, slender cylinder winding down into the lower body of the Nautilus whorl.
"Watch!" said Rador.

He motioned me into the vehicle and took a place beside me.

The driver touched the lever; a stream of coruscations flew from the ball down into the cylinder.

The shell started smoothly, and as the tiny torrent of shining particles increased it gathered speed.
"The corial does not touch the road," explained Rador.