"You might call it stupid," was his comment.
"Exactly. Nobody could be expected to see danger to the state in an order to buy Nepaul rice or Sumatra cigars. It's all right and runs on greased rails, till Grindley comes along. He turns over that La Motte of hers, till he notices some minute pencil-marks on one of the green advertisement pages at the back. The marks were so small that no eyes but Grindley's would have noticed them at all. And even Grindley couldn't read them without a magnifying glass." Singleton leaned over suddenly till he could command the avenue, stretching, sun-flecked, empty to the gates.
"Do you always hear the motor before it gets to the plantation?"
"Always."
"Well, the kind of thing that came out under the glass was: 'Market dull—Ascertain R—activity.' R," interpreted Singleton, "meaning Hosyth, of course. 'Prices falling—Leaving Southampton. Advise purchase—Report to Seventy-Six.'
"Seventy-six is the number of the German agent at Amsterdam. We've learned a good deal since we discovered that is where seventy-six hangs out. This message, for instance,"—he nodded at the one between them on the table—"says, 'Advise immediate purchase Erie at 22-1/4—3/4 and steel 129-5/8, market rising.' It's clear, according to the La Motte code, that something's got to be reported instantly to the German secret service agent at Amsterdam. The question is what? Even if we intercepted the message, we shouldn't be any the wiser. Or, rather, we shouldn't have been, if Grindley hadn't gone juggling with the numbers of the stock quotations till it occurred to him, after trying the thing twenty other ways." He stopped.
"Yes," Napier threw in. "I've been wondering why you tell me all this."
His smile was slightly abstracted.
"It's all right, I thought I heard a motor," said Singleton. He met Napier's eyes. "It's my business to know men, and before it was my business I knew you." That was the sole reference made to the Oxford episode. "Grindley's got an idea," Singleton went on and his face reflected the brilliance of it, "that the consonants in the occasional short-code words interpolated into some of the messages—words like Tubu, and so on—stand for the class of ship the submarines are to look out for. Tubu equals Torpedo boat. Kreuzer, Kleinkreuzer, Zerstorer, and so on, are indicated, we think now, in the same way."
Napier made no pretense at sharing Singleton's delight in these speculations.