eyes around the circle until they
met it."

Carstairs sat up.

"Where?" he asked.

"Begin as I told you and sweep your eyes around the circle."

"Ah, I see it now! Or maybe it's just a mote in the dancing sunbeams."

"Oh no, it's not. Watch it grow. It's an aeroplane, and I'd wager
everything against next to nothing that it's the one that left a little
while ago. Whatever it went to do it's done."

"Upon my soul, I think you're right. It is growing as you say. Now the
dot becomes a black spot as big as an egg, now it grows to the size of
your hand, and now the shape of a flying machine, coming at terrific
speed, emerges. The whole process of departure is reversed."

"And it's making straight for that overhanging group," said Wharton.

John watched the big birds of prey await the messenger, and again he
longed intently for Lannes' powerful glasses. The returning machine was
received by the others which formed a circle about it, and for some
minutes they hung there in close company.

His nerves began to quiver again with excitement. He was sure that it
was a menace. The small aeroplane would not have gone away on a mission
without some excellent reason. Sure of his leafy covert he stood up, and
watched the group which now circled almost exactly over their heads.
Carstairs and Wharton stood beside him, and again they turned to him as
the leader, now that it was an affair of the air.

"What do you make of it?" asked Carstairs, anxiously.

"It means harm, some new method of attack," said John, "but for the life
of me I can't guess what it is."

"Then we've merely got to wait," said Wharton.

The three were standing close together, and a chill seemed to pass from
one to another. That great danger threatened not one of the three
doubted, and its mysterious character made it all the more formidable.

The aeroplanes drew apart a little and again circled about lazily. John
began to have a hope that nothing would happen after all, when suddenly
he saw a flash in the thickets and heard a stunning roar. A piece of
metal whistled past his head, and leaves and twigs fell in a shower.

Acting partly from reason and partly from impulse he seized both Wharton
and Carstairs and dragged them to the ground.

"A bomb!" he cried. "I had forgotten about bombs, although I've seen
them used before. They had none with them and the little aeroplane went
back to a hangar somewhere for a supply! They'll drop more and we'll be
saf