and the zero—­”

[Illustration:  Cryptographic symbol]

A sudden excitement stirred Harren; he leaned over the paper, gazing earnestly at the cipher; the Tracer rose and glanced around the room as though in search of something.

“Is there a telephone here?” he asked.

“For Heaven’s sake, don’t give this up just yet,” exclaimed Harren.  “These things mean numbers; don’t you see?  Look at that!” pointing to a linked pair of seals,

[Illustration:  Cryptographic symbol]

“That means the number nineteen!  You can form it by using only the crossed lines of the seal.

[Illustration:  Cryptographic symbol]

Don’t you see, Mr. Keen?”

“Yes, Captain Harren, the cipher is, as you say, very plain; quite as easy to read as so much handwriting.  That is why I wish to use your telephone—­at once, if you please.”

“It’s in my bedroom; you don’t mind if I go on working out this cipher while you’re telephoning?”

“Not in the least,” said the Tracer blandly.  He walked into the Captain’s bedroom, closing the door behind him; then he stepped over to the telephone, unhooked the receiver, and called up his own headquarters.

“Hello.  This is Mr. Keen.  I want to speak to Miss Borrow.”

In a few moments Miss Borrow answered:  “I am here, Mr. Keen.”

“Good.  Look up the name Inwood.  Try New York first—­Edith Inwood is the name.  Look sharp, please; I am holding the wire.”

He held it for ten full minutes; then Miss Borrow’s low voice called him over the wire.

“Go ahead,” said the Tracer quietly.

“There is only one Edith Inwood in New York, Mr. Keen—­Miss Edith Inwood, graduate of Barnard, 1902—­left an orphan 1903 and obliged to support herself—­became an assistant to Professor Boggs of the Museum of Inscriptions.  Is considered an authority upon Arabian cryptograms.  Has written a monograph on the Herati symbol—­a short treatise on the Swastika.  She is twenty-four years of age.  Do you require further details?”

“No,” said the Tracer; “please ring off.”

Then he called up General Information.  “I want the Museum of Inscriptions.  Get me their number, please.”  After a moment:  “Is this the Museum of Inscriptions?”

* * * * *

“Is Professor Boggs there?”

* * * * *

“Is this Professor Boggs?”

* * * * *

“Could you find time to decipher an inscription for me at once?”

* * * * *

“Of course I know you are extremely busy, but have you no assistant who could do it?”

* * * * *

“What did you say her name is?  Miss Inwood?”

* * * * *

“Oh!  And will the young lady translate the inscription at once if I send a copy of it to her by messenger?”