Free Murray Leinster (Duke Classic SiFi) by Operation: Outer Space

visible during all its
flight. Its trail should have been a thick red line. Instead, the red
sparks were so far separated—the trail was so attenuated that it was
visible only from a spot near its base. The observatory voice said more
blankly still:
    "
Hey! I've picked up the trail! I can't see it nearby, but it seems to
start, thin, about fifty miles up and go on away from there! That
rocket shouldn't ha' gone more than twenty miles! What happened?
"
    "
Watch for the microwave signals
," said Jones' voice in Cochrane's
headphones.
    The voice from the observatory squeaked suddenly. This was not one of
the highly-placed astronomers, but part of the mechanical staff who'd
been willing to do an unreasonable chore for pay.
    "
Here's the blip! It's crazy! Nothing can go that fast!
"
    And then in the phones there came the relayed signal of the auto-beacon
in the vanished rocket. The signal-sound was that of a radar pulse,
beginning at low pitch and rising three octaves in the tenth of a
second. At middle C—the middle of the range of a piano—there was a
momentary spurt of extra volume. But in the relayed signal that louder
instant had dropped four tones. Cochrane said crisply:
    "Jones, what speed would that be?"
    "
It'd take a slide-rule to figure it
," said Jones' voice, very calmly,
"
but it's faster than anything ever went before.
"
    Cochrane waited for the next beep. It did not come in ten seconds. It
was easily fifteen. Even he could figure out what that meant! A
signal-source that stretched ten seconds of interval at source to
fifteen at reception ...
    The voice from the observatory wailed:
    "
It's crazy! It can't be going like that!
"
    They waited. Fifteen seconds more. Sixteen. Eighteen. Twenty. The beep
sounded. The spurt of sound had dropped a full octave. The
signal-rocket, traveling normally, might have attained a maximum
velocity of some two thousand feet per second. It was now moving at a
speed which was an appreciably large fraction of the speed of light.
Which was starkly impossible. It simply happened to be true.
    They heard the signal once more. The observatory's multiple-receptor
receiver had been stepped up to maximum amplification. The signal was
distinct, but very faint indeed. And the rocket was then traveling—so
it was later computed—at seven-eighths of the speed of light. Between
the flat cone on the front of the distress-torpedo, and the flat cone on
the ground, a field of force existed. The field was not on the back
surface of the torpedo's cone, but before the front surface. It went
back to the moon from there, so all the torpedo and its batteries were
in the columnar stressed space. And an amount of rocket-push that should
have sent the four-foot torpedo maybe twenty miles during its period of
burning, had actually extended its flight to more than thirty-seven
hundred miles before the red sparks were too far separated to be traced
any farther, and by then had kicked the torpedo up impossibly close to
light-speed.
    In a sense, the Dabney field had an effect similar to the invention of
railways. The same horsepower moved vastly more weight faster, over
steel rails, than it could haul over a rutted dirt road. The same
rocket-thrust moved more weight faster in the Dabney field than in
normal space. There would be a practical limit to the speed at which a
wagon could be drawn over a rough road. The speed of light was a limit
to the speed of matter in normal space. But on a railway the practical
speed at which a vehicle could travel went up from three miles an hour
to a hundred and twenty. In the Dabney field it was yet to be discovered
what the limiting velocity might be. But old formulas for acceleration
and increase-of-mass-with-velocity simply did not apply in a Dabney
field.
    Jones rode back to Lunar City with Cochrane and Holden and Babs. His
face was dead-pan.
    Babs tried to recover the mien and manner of the perfect secretary.
    "Mr. Cochrane," she said professionally, "will you want to read