time,
he moved, lest he snap a stick or strike a stone with his foot. As
soon as he was clear of the brush, he faced about, and crawled into the
darkness.

The spy, meantime, was proceeding rapidly in reassembling his car.
Henry heard the windshield go up and the top being fastened. He heard
the baggage lid snap into place. Then he heard the spy swearing in a
low voice. Henry stopped, still as a hunted rabbit.

"_Donnerwetter!_" he heard the man say. "I've lost that dollar."
There was a pause. Then came the words, "I'm not going to hunt for it
anyway. Somebody would see my light sure. And if anybody does find
it, he'll never guess what it is."

Exultantly Henry rose to his feet, and crouching low, ran with soft,
swift tread to his motorcycle. He had the dollar. The owner believed
it was lost. Never was such luck. Trembling all over, he fastened his
cane to the frame of his wheel, trundled his car to the road and ran
with it in the direction he had come. He pushed it until his breath
was coming in gasps. Then he turned into the woods and hid. He would
take no chance of being seen by the spy or by any accomplice who might
have followed him. Presently Henry heard the motor-car pull out into
the road and go speeding back toward Manhattan. A quarter of an hour
later Henry returned to the highway, switched on his light, and was
soon bowling along on his way to his fellows and his chief, feeling
that he had in his keeping the future safety of a nation.

CHAPTER XIV

THE RIDDLE SOLVED

In the house above the hawk's nest, four boys and a man sat far into
the night, examining a marked dollar and trying to unravel the secret
of the scratches. From hand to hand the dollar passed and was examined
now this way, now that; but the little group could see no meaning in
the apparently aimless marks on the silver coin. Had some of them not
seen this dollar marked and its message deciphered and sent vibrating
through the air, they would have refused to believe that the coin
before them carried a message at all. It looked like any dollar that
has accidentally become marked.

"To-morrow," said Captain Hardy, "we will turn the dollar over to the
secret service, and doubtless their experts will solve the problem
quick enough. But I certainly wish we could unravel this thing
ourselves. Wouldn't it be an achievement for the wireless patrol!"

"It's going to be," declared Roy positively. "We're going to solve