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.