cinders."

The engineer squinted through an opal glass shutter into one of the
tunnels, through which the anti-gravitation current was pouring. "If you
didn't know any more about buildings than you do about machinery,
Jackson," he grunted, because of his squatting position, "I'd hate to
live in one of your houses!"

The architect smiled grimly. "You're living in one of 'em right now,
Smith," said he; "that is, if you call this car a house."

Smith straightened up. He was an unimportant-looking man, of medium
height and build, and bearing a mild, good-humored expression. Nobody
would ever look at him twice, would ever guess that his skull concealed
an unusually complete knowledge of electricity, mechanisms, and such
practical matters.

"I told you yesterday, Jackson," he said, "that the air surrounding the
earth is chock full of electricity. And--"

"And that the higher we go, the more juice," added the other,
remembering. "As much as to say that it is the atmosphere, then, that
protects the earth from the surrounding voltage."

The engineer nodded. "Occasionally it breaks through, anyhow, in the
form of lightning. Now, in order to control that current, and prevent it
from turning this machine, and us, into ashes, all we do is to pass the
juice through a cylinder of highly compressed air, fixed in this wall.
By varying the pressure and dampness within the cylinder, we can
regulate the flow."