so is
pure gold."

"Flatterer!" Her low, entrancing chuckle bubbled over. "But you know I
just revel in it. I'll kiss you for that!"

"It _is_ awfully lonesome out here, without even a star to look at," she
went on, after a time, then laughed again. "If the Cranes and Shiro
weren't along, we'd be really 'alone at last,' wouldn't we?"

"I'll say we would! But that reminds me of something. According to my
figures, we might have been able to detect the Fenachrone on the last
test, but we didn't. Think I'll try 'em again before we turn in."

Once more he flung out that tenuous net of force, and as it reached the
extreme limit of its travel, the needle of the micro-ammeter flickered
slightly, barely moving off its zero mark.

"Whee! Whoopee!" he yelled. "Mart, we're on 'em!"

"Close?" demanded Crane, hurrying into the control room upon his beam.

"Anything but. Barely touched 'em--current something less than a
thousandth of a micro-ampere on a million to one step-up. However, it
proves our ideas are O. K."

The next day--_Skylark III_ was running on Eastern Standard Time, of the
Terrestrial United States of America--the two mathematicians covered
sheet after sheet of paper with computations and curves. After checking
and rechecking the figures, Seaton shut off the power, released the
molecular drive, and applied acceleration of twenty-nine point six oh
two feet per second; and five human beings breathed as one a profound
sigh of relief as an almost-normal force of gravitation was restored to
them.

"Why the let-up?" asked Dorothy. "They're an awful long ways off yet,
aren't they? Why not hurry up and catch them?"

"Because we're going infinitely faster than they are now. If we kept up
full acceleration, we'd pass them so fast that we couldn't fight them at
all. This way, we'll still be going a lot faster than they are when we
get close to them, but not enough faster to keep us from maneuvering
relatively to their vessel, if things should go that far. Guess I'll
take another reading on 'em."

"I do not believe that I should," Crane suggested, thoughtfully. "After
all, they may have perfected their instruments, and yet may not have
detected that extremely light touch of our ray last night. If so, why
put them on guard?"

"They're probably on guard, all right, without having to be put
there--but it's a sound idea, anyway. Along the same line I'll release
the fifth-order screens, with the fastest possible detector