.

Consequently, the flatter the trajectory the farther it will go. Tom's
object, then, was to flatten the trajectory, by lowering the muzzle of
the gun, in order to attain greater distance.

"If this doesn't do the trick, we'll try it with the muzzle a bit
lower, and with a trifle more powder," he said to Ned, as he was about
to fire.

The young inventor was not a little nervous as he prepared to press the
button this time. It was a heavier charge than any used that day,
though the same quantity had been fired on other occasions with safety.
But he was not going to hesitate.

Coincident with the pressure of Tom's fingers there seemed to be a
veritable earthquake. The ground swayed and rocked, and a number of the
spectators staggered back. It was like the blast of a hundred
thunderbolts. The gun shook as it recoiled from the shock, but the
wonderful disappearing carriage, fitted with coiled, pneumatic and
hydrostatic buffers, stood the strain.

Following the awful report, the terrific recoil and the howl of the
wind as it rushed into the vacuum created, there was an intense
silence. The projectile had been seen by some as a dark speck, rushing
through the air like a meteor. Then the wireless operator could be seen
writing down a message, the telephone-like receivers clamped over his
ears.

"Something happened, all right!" he called aloud. "That shot hit
something."

"Not one of the ships!" cried Tom, aghast.

"I don't know. There seems to be some difficulty in transmitting.
Wait--I'm getting it: now."

As he ceased speaking there came from underneath the great gun the
sound of confused shouts. Tom and Ned recognized Koku's voice
protesting:

"No--no--you can't come in here! Master said no one was to come in."

"What is it, Koku?" yelled Tom, springing to the speaking tube
connecting with the powder magazine, at the same time keeping an eye on
the wireless operator. Tom was torn between two anxieties.

"Someone here, Master!" cried the giant. "Him try to fix powder. Ah, I
fix you!" and with a savage snarl the giant, in the concrete chamber
below, could be heard to attack someone who cried out gutturally in
German:

"Help! Help! Help!"

"Come on, Ned!" cried Tom, making a dash for the stairs that led into
the magazine. There was confusion all about, but through it all the
wireless operator continued to write down the message coming to him
through space.

"What is it, Koku? What is it?" cried Tom, plu