the sweeping second hand of the chronometer, Tom called out,
"Blast off minus five--four--three--two--one--_zero_!"

With a mighty roar, all main rockets of the spaceship exploded into
life. Shuddering under the sudden surge of power, the ship rose from the
ground, accelerated at the rate of seven miles per second, and arrowed
into the sky, space-borne!

On the Academy spaceport, ships of Squadron L began to blast off one by
one behind the _Polaris_ at ten-second intervals. Three rocket cruisers,
six destroyers, and twelve rocket scouts. The explosive blast of one
hardly rolling away across the surrounding hills before another
deafening blast lifted the next space vessel away from Earth.

Aboard the _Polaris_, Roger was busy over the chart table plotting the
course when Strong appeared at his side.

"Have that course for you in a minute, sir," said Roger. He turned to
the astrogation prism and made careful observations of Regulus, the
fixed star always used in astrogation. He jotted several numbers down on
a piece of paper, rechecked them against a table of relative values and
handed the papers to Strong.

The captain immediately opened the teleceiver and relayed the
information to other ships of the squadron. After the _Polaris_ had made
the course change, the ships followed, taking positions all around the
lead vessel.

Like fingers of a giant hand, the Solar Guard squadrons converged on the
reported position of the disabled _Avenger_. From every ship, radar
scanners probed the space ahead with invisible electronic fingers for
contact with the target. On the _Polaris_, Strong, his nimble brain
figuring Coxine's possibilities of escape, hunched over the chart table
and worked at plotting alternate courses on which he could send pursuit
squadrons on a moment's notice. One thing worried Strong, and that was
if Coxine should repair his ship and make the security of the asteroid
belt before they could reach him, it would be almost impossible to track
him through that tortuous maze of space junk.

Squadron Ten was the first to sight the enemy spaceship, though it was
too far away to attack. The commander reported his finding to Strong
immediately.

"We still have quite a way to go before we reach him, Strong. But if our
luck holds out, we might be able to pin him down in a wide circle."

Strong studied the chart and marked the position of the _Avenger_ just
reported. He compared the position to that of the other