huge bulk
of the airship, as long as a moderate sized ocean liner. She presented a
perfect target.

"Now!" said Harry.

And at once Dick began dropping projectiles they had found in the
aeroplane--sharply pointed shells of steel. Harry had examined these--he
found they were really solid steel shot, cast like modern rifle bullets,
and calculated to penetrate, even without explosive action, when dropped
from a height.

From the first two that Dick dropped there was no result. But with the
falling of the third a hissing sound came from below, and as Dick rapidly
dropped three more the noise increased. And they could see the lights
flying--plainly the men were running from the monster. Its bulk lessened as
the gas escaped from the great bag and then, in a moment more, there was a
terrific explosion that rocked the monoplane violently. Had Harry not been
ready for it, they might have been brought down.

But he had been prepared, and was flying away. Down below there was now a
great glare from the burning wreckage, lighting up the whole scene. And
suddenly there was a sharp breaking out of rifle fire. At first he thought
the men below had seen them, and were firing upward. But in a moment he saw
the truth. Bray Park had been attacked from outside!

Even before they reached the ground, in the meadow where Harry and Jack had
emerged from the tunnel, the firing was over. But now a search-light was
playing on the ground on the opposite bank, and Harry and Dick saw, to
their wonder and delight, that the ground swarmed with khaki-clad soldiers.
In the same moment Jack ran up to them.

"The soldiers had the place surrounded!" he cried, exultingly. "They must
have believed your letter after all, Harry! Come on--there's a boat here!
Aren't you coming over?"

They were rowing for the other shore before the words were well spoken.
And, once over, they were seized at once by two soldiers.

"More of them," said one of the soldiers. "Where's the colonel?"

Without trying to explain, they let themselves be taken to where Colonel
Throckmorton stood near the burning wreckage. At the sight of Harry his
face lighted up.

"What do you know about this?" he asked, sternly, pointing to the wrecked
airship.

Harry explained in a few words.

"Very good," said the colonel. "You are under arrest--you broke arrest this
morning. I suppose you know that is a serious offence, whether your
original arrest was justified or not?"

"I felt I