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 it.
We've just got to. We'll show those secret service men that boys are
some good after all."
But the word was easier than the deed. Puzzle their brains as they
might, search the dollar as they would, they still found no key to the
language it spoke.
"Tell me again what the message was," demanded Henry for the twentieth
time, and Lew once more passed to Henry the slip of paper on which he
had written the message, both in cipher and deciphered, the message he
had picked from the air. It read as follows: TRPSLOWAOSEDONBADATSTITY.
T R P S L O
W A O S E D
O N R A D A
T S T I T Y
Long Henry studied the piece of paper, softly reading the message to
himself. "Two transports sailed to-day. How did that automobile
driver get that message from this dollar?" he asked himself, and again
he picked up the coin and turned it in his hand. "If only we had that
disc," he sighed, "or a duplicate."
At the word "duplicate," Roy pricked up his ears. "Maybe we can make
one," he said.
"Likely!" scoffed Lew.
"You never know till you try," rejoined Roy. Then he turned to Willie
and demanded, "What was the disc like that you saw?"
"If I knew, I'd make one," said Willie.
"Well," said Roy in a tone of disgust, "you know whether it was a foot
across or not, and whether it was round or square."
"It was round, of course," said Willie, "and the same size as the
dollar. I told you that before."
"We can make a disc the size of a dollar, anyway, even if it doesn't
get us anywhere," said Roy, putting the coin on a sheet of paper and
outlining it with a pencil. Then with scissors he cut the disc out.
"You saw that disc, or one like it, Henry," continued Roy. "What did
it look like to you?"
"Just like a spider-web, as Willie says," replied Henry.
"All right, we'll make a spider-web," said Roy.
He seized his pencil, made a dot in the centre of the disc, and from
the dot drew straight lines that radiated in different directions.
Then he drew a number of concentric circles about his dot.
"I don't see how that helps any," he said, examining his drawing. "Yet
that's the kind of thing they used to mark that dollar."
From hand to hand the paper passed, and each boy compared it with the
dollar. But none was any the wiser when he had finished. Their
leader, meantime, sat with his head in his hands, studiously turning
the matter over and over in his mind. For a long time he could make
nothing of it.
After a while he looked up. "Let me see that paper," he said.
Roy handed him the little disc. Captain Hardy laid the disc beside the
dollar on the table, and painstakingly examined again the marks on the
coin. After a time he took a sheet of paper and across it in a row
wrote down the letters of the alphabet. Then he picked up the message
and made check marks below the letters in his alphabet as he found
those letters in the message. When he had gone through the message,
his paper looked like this:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
/ // / / /// /// / /
/ / / ///
/ / //
/
He picked it up and studied it. "Four T's," he said, "three S's, three
A's, and three O's. That ought to give us a clue."
Again he turned to the dollar and began to study it, turning it slowly
round, counting the scratches this way and that, making geometric
figures of them. Four heads peered over his shoulder as he worked
silently with his pencil.
"I can make nothing of it," he said after a time.
Again he sat in deep thought, his fellows meanwhile once more examining
dollar and disc and the figures their leader had made on the paper.
"Four T's," repeated Captain Hardy after an interval. "Surely that
ought to give us a clue."
Once more he studied the penciled disc. Then he turned to the dollar
and again examined its markings. He suddenly exclaimed, "Here are four
scratches in a straight row." His eyes began to shine. Slowly he
turned the coin. "And here are three in another row, like this," and
he indicated the positions of the scratches on the paper disc. "You
notice that each row runs from the centre of the coin toward the edge.
Let's see if there are any more rows."
Very slowly he turned the dollar. "And there are three in a row," he
said, indicating the scratches with his pencil, "and here are three
more. You notice that the rows all radiate from the centre, like
spokes in a wheel. I believe we are getting somewhere, boys."
"'Like spokes in a wheel,'" repeated Roy to himself. "Rows of letters
like spokes in a wheel. Four scratches in one row or spoke--these must
be the four T's. Three scratches in these other rows must be O's and
A's and S's. I've got it! I've got it!" he suddenly shouted. "There
must be as many spokes as there are letters in the alphabet."
"I believe you are right, Roy," said Captain Hardy, looking up with a
gleam in his eyes. "That's exactly what I am beginning to think.
We'll soon see if you are right. Make me another disc."
With a pocket rule he measured the diameter of the dollar.
"Practically an inch and a half," he announced, putting down the
figures 1.5 on paper. He multiplied those figures by 3.1416.
"That," said he, pointing to the resulting figures, 4.71+, "represents
the circumference of a dollar. Now we'll divide the circumference by
26, the number of letters in the alphabet."
He performed the division. "Eighteen one-hundredths of an inch," he
announced. "That's practically a scant fifth of an inch. We'll call
it so, anyhow," he continued as he marked off the space on a sheet of
paper with his rule. "Each sector," he said, "gets exactly that amount
of space on the circumference."
He pulled open the drawer of the desk and began to rummage through a
tray full of pens, pencils, and other drawing materials. "I wonder if
there is such a thing as a pair of dividers here," he remarked. And a
moment later he exclaimed "Good!" and drew forth the compasses he was
looking for.
He set his dividers according to the space he had marked off with his
rule, then proceeded to divide the circumference of the new paper disc.
When he had gone completely round the disc, he seized pencil and ruler
and began to draw lines from centre to circumference--the spokes of his
wheel--each spoke running from the dot in the centre to one of the
points indicated by the dividers. When he had finished, the disc was
divided into twenty-six equal sectors, like tiny pieces of a pie.
"We shall soon know whether you are right or not in your guess, Roy,"
said Captain Hardy.
He laid the dollar beside the disc and began to copy on the disc the
marks on the dollar. "We'll put four marks in this sector," he said,
making four dots with his pencil. "They are like those four scratches
here," and he pointed to the four marks in a row on the dollar. "They
must be four T's. At any rate we'll call this the T sector. On the
dollar you notice this row of three scratches--the next sector to the
left of the T sector. You remember we had three O's, three A's, and
three S's. These three scratches must, therefore, be O's, A's, or S's.
Since they are next to the T's, they are doubtless S's. I'll mark the
sector so anyway. That gives us the T sector and the S sector. If we
are on the right track, then the sector to the left of the S space is
the R sector, and so on. I'll mark the disc that way, anyhow."
Slowly he turned the disc around, putting a letter at the bottom of
each sector. When he had finished, he had completed the alphabet.
About him clustered his four comrades, too deeply interested to speak.
They hardly even breathed.
"Take this paper, Roy," said Captain Hardy, "and tell me how many times
each letter in the message appears."
Roy took the paper on which Captain Hardy had made his numerical
enumeration. "Three A's," he said.
Captain Hardy made three marks in the A sector.
"No B's, no C's, and two D's."
The D's were scored. So they went through the alphabet. When they
were done, the markings on the disc were practically a duplicate of
those on the dollar, for Captain Hardy studied the dollar each time
before marking the paper disc.
"That's it," cried Willie. "That's it exactly."
"It's right so far as it goes, Willie," said their leader, "but we
haven't all of it yet. Suppose I hand you a disc with four T's, three
S's, two Z's, three L's, and so on. Could you make a message out of
it?"
Willie studied the disc on the desk. "No," he said, "I couldn't. I
shouldn't know how to arrange the letters to make words out of them."
"Neither would anybody else," continued Captain Hardy. "Those spies
have some way of knowing how to tell the order in which to read these
letters."
For some time he sat studying the scratches on the dollar. The four
boys were quiet as mice, each trying to solve the problem that stood
between them and complete mastery of the cipher.
"You said that the metal disc resembled a spider's web," began Captain
Hardy, talking more to himself than to the boys. "We know what the
straight lines--the spokes--are for. The concentric circles must be to
indicate the order of the letters. Let me see." Again he studied the
dollar closely. "Some of these marks are near the centre of the disc,
some half-way between centre and circumference, and some close to the
outer edge. I believe the secret lies there."
"Listen!" cried Willie of a sudden. "When a spider spins a web, she
begins at the centre and works outward. Maybe these spies write their
messages in the same way."
"Willie," cried Captain Hardy, "you've hit it exactly. You're as good
a reasoner as you are an observer. Now we'll begin at the centre and
spin this message outward. What's the first letter?"
"T," said four voices together.
The captain took his dividers and found the scratch nearest the centre
of the disc. In the same sector with this scratch were three other
scratches in a line.
"It's a T," he announced, "just as it should be."
With his dividers he found the letter next nearest to the centre. It
stood alone. "That's a W," he announced.
Rapidly he located the scratch the third nearest to the centre. "And
that's an O," he said, looking up with flashing eyes. "We need go no
farther. We have the entire secret. We have deciphered their cipher."
A cry of exultation arose.
"To-morrow," continued Captain Hardy, "we will get a piece of
transparent celluloid and make a disc like their own. We can ink in
the circles and the radius lines and our disc will be almost a
duplicate of theirs, except that our disc will be solid while their
discs have open spaces between the circles. But that is only a detail.
We can read their cipher as well as if we had one of their own discs."
"Wait," cried Willie, as his comrades started to cheer again. "What is
the scratch on the milled edge of the dollar for?"
"That," replied Captain Hardy, "is to indicate how the disc is to be
placed on the dollar. That scratch is exactly between the Z and the A
sectors. It shows where the alphabet begins. Now we have their entire
secret."