capacity.

In this mortar lay a quantity of powdered stuff, which Garwood
had evidently been grinding before their arrival. Now he poured
out a heaping handful of the chlorate crystals, dropping them
on top of the mixture in the mortar.

"A few turns---a little more fatigue of the wrist---and I am the
world's master---its owner!" cried Garwood exultantly.

"Ker-choo!" sneezed Tom Reade at the worst possible moment.

Amos Garwood turned like a flash, tottering to his feet.

"Spies! Traitors! Ingrates!" he gasped in hoarse terror.

"Nothing at all like it," Dick replied, with a pleasant smile.
"Mr. Garwood, we boys are playing in these woods. If we've meddled
with your affairs you'll pardon us, and let us pass on, won't you?"

"Didn't you try to find me here?" demanded Garwood, suspicious still.

"I give you my word of honor that we didn't, sir," answered Dick.
"Until a moment ago we hadn't any idea that you were within
fifty miles of this spot. You see, sir, we're playing Indians
and whites. We're the big Injuns, even if we don't look it.
And behind us, somewhere on our trail, is Captain Greg Holmes,
with a company of his brave soldiers, trailing us relentlessly."

"Soldiers?" quivered Amos Garwood, his face going ashen. Then
his face suddenly took on a look of intense exultation. "Soldiers?"
he repeated. "It couldn't be better. It is on soldiers that
my amazing discovery should be proved. But I waste time---and
loss of time may be fatal to all my plans. A few turns, and my
discovery is ready. I can then defy whole armies, if necessary!"

Sweeping the mortar around within reach, so that he could work
and watch the Grammar School boys at the same time, Amos Garwood
began to grind his pestle into the mixture with feverish energy.

Then all of a sudden the very earth shook and rocked. Big Injun
Prescott and his two braves were in the center of the biggest explosion
they had ever heard!

Chapter XIV

"CRAZY AS A POROUS PLASTER"

It was terrific, and yet the only effect on the bench on which
the mortar lay was to knock the board sideways from the boxes.
The mortar became as powder itself, though not a splinter was
raised from the wood.

From the lips of Amos Garwood a fearful yell went up. He plunged
headlong a few feet, then lay on the ground, feebly nursing his
right hand with his left.

As for Dick, Dave and Tom, their ears rang with the noise until
they felt as though surely their ear-drums ha