r him to catch the rays strongly
on his small mirror.

Now, in the Army signaling work, one branch has to do with
heliographing; that is, flashing a message by means of reflected rays of
the sun's light.

Swiftly enough the young sergeant caught the flash, and found to his
delight that he was able to throw a fairly long flash.

"Camp in hands of ruffians. Help quick!"

[Illustration: The Mirror Was Shot From Hal's Hand.]

Despite his tremendous excitement, Sergeant Overton endeavored to steady
his right hand enough to enable him to send the message quite clearly.

Again and again he flashed the message, until one of the invaders,
glancing up at the tree top, caught sight of the work that was going on.

"That kid's trying to send word to some one," guessed the leader. "Here,
cub, hand me that rifle."

Crack!

Smash!

It was a true shot, though how much of it was due to luck Sergeant Hal
could not surmise.

But the glass was shot from his hand, the splintered bits falling to the
ground.

"Next shot for you, kid!" warned the marksman below.

"Yes?" mocked Overton.

"Surest thing in the world? Coming down, or shall I bring you down?"

Crack!

Hal drew his own weapon up, firing as the sight passed the human target.

It was a close shot, the revolver bullet carrying away the fellow's
cloth cap.

"I'm firing too high," spoke Hal as composedly as though he did not feel
any excitement. "I'll fire for your belt line after this."

That was too much for the ruffian's composure. He turned, running in a
zig-zag line.

So Hal held his fire, awaiting results for a moment. As he waited he
felt for his revolver ammunition.

Then he made a sickening discovery. He had no revolver ammunition beyond
the five cartridges remaining in the cylinder of his weapon.

As for the invaders, they had more than three hundred rounds of rifle
ammunition now at their disposal.

And they had fled to cover, too, but now Sergeant Overton had the
uncomfortable conviction that three rifles were trained on him.

"Now, come down out of that tree on the double quick!" commanded the
leader of the invaders.

"My coming will suit myself only," boasted Hal in a tone conveying ten
times the confidence that he felt.

"That shot of yours may start help this way," continued the leader
threateningly. "We ain't going to take any chances. Start on the second,
or we'll begin shooting, and keep it up until we tumble you out of that
tree."