fifteen minutes for the water to reach the boiling point,
while they nervously held their watches. They could keep track of
minutes and hours, although there was no longer day and night in their
lives. According to their figures, they now ate dinner at three o'clock
in the morning, and went to bed in the early afternoon.

They held their breath when the steam valve was opened. It moved slowly
under Dick's fingers, while a thousand questions raced through every
mind.

"Would it silence the blasts? Would it put them out of commission
permanently? Was that moment, and the turning of that valve, the end of
existence for them all?"

Dick glanced at the gauge on the tube, then jerked the valve shut. The
pressure was still far below that of the fuel. He turned the heating
unit on full, and watched the gauge climb higher. They didn't understand
the numerals of the domed cities, but knew the pressure was getting
terrifically high.

When he opened the valve again, the steam gauge _did not rise_! It held
almost steady. The hiss of escaping steam, sounded through the heavy
metal faintly.

The tubes began to fire spasmodically! Dick bit his lips, as he opened
the valve a little wider. John McCarthy wiped the sweat from his
forehead, as every face turned white as chalk.

_They fired evenly again!!!_ The steam was working through the
mixture--_discharging through the blasts_!

* * * * *

They felt their bodies sway under the effects of acceleration and
exultance filled them. There was _some_ reaction, at least!

Morquil appeared on the ramp, his face lighted by a smile. "_What have
you done?_ The ship is traveling at _almost twice the speed that it was
before_! Is it all right?"

Dick sat down hard. Not a man in the crowd was able to answer. Success
had left them speechless. Barrow was the first to recover his voice.

"Are you _sure_?"

"Yes, Dick! We took three separate observations, and each showed the
same result--almost _double_ normal speed! Does it mean what you wanted?
_Can we reach the domes?_"

"I hope so, Morquil. If the steam has made _that_ much difference, we'll
get there without trouble. The water must be conserved as much as
possible--and hope that it lasts. Whether it increases the power of the
fuel, or simply creates an additional body to drive against, is not
important. _We're getting there!_"

CHAPTER VII

_Jupiter and Trouble!_

The huge ship circled the