"By George! that's so! A variation of the 'clock code' as well as Verne's idea. Here, read off the letters and I'll put them on the board with the figures representing Hohenzollern underneath. Take the first fifteen as before." When they had finished, the blackboard bore the following, the first line being the original code letters, the second the letter figures of these, and the third the figures of the word "Hohenzollern" with the first "h" repeated for the fifteenth letter: I i i t f b b t t x o r q w s b b I ii t f bb tt x o r q w s bb 9 35 20 6 28 46 24 15 18 17 23 19 28 8 15 8 5 14 26 15 12 12 5 18 14 8 "Why thirty-five for that double 'i' and twenty-eight for the double 'b's'?" asked Barlow. "Add twenty-six--the total number of letters in the alphabet--to the letter figure for the letter itself," said Thurber. "That's the one beauty of this code, one of the things which helps to throw you off the scent. Now subtracting the two lines we have: "1 20 12 1 14 20 9 3 6 12 5 5 20 "We've got it!" he cried an instant later, as he stepped back to look at the figures and read off: "A t l a n t i c f l e e t "It was a double code, after all," Thurber stated when he had deciphered the entire message by the same procedure and had reported his discovery to the Secretary of the Navy over the phone. "Practically infallible, too, save for the fact that I, as well as Doctor Albert, happened to be familiar with Jules Verne. That, plus the doctor's inability to rely on his memory and therefore leaving his key words in his brief case, rendered the whole thing pretty easy." "Yes," thought Gene, "plus my suggestion of the September word, rather than the October one, and plus Paula's quick wit--that's really all there was to it!" But he kept his thoughts to himself, preferring to allow Thurber to reap all the rewards that were coming to him for the solution of the "double code." * * * * * "Do you know what the whole message was?" I inquired, as Quinn stopped his narrative. "You'll find it pasted on the back of that copy of _The Giant Raft_," replied the former operative. "That's why I claim that the book ought to be preserved as a souvenir of an incident that saved millions of dollars and hundreds of lives." Turning to the back of the Verne book I saw pasted there the following significant lines: Atlantic Fleet sails (from) Hampton Roads (at) six (o'clock) morning of seventeenth. Eight U-boats will be waiting. Advise necessary parties and be ready (to) seek safety. Success (of) attack inevitable. "That means that if Thurber hadn't been able to decipher that code the greater part of our fleet would have been sunk by an unexpected submarine attack, launched by a nation with whom we weren't even at war?" I demanded, when I had finished the message.