"Listen to this," and he read aloud, translating as he went along.
"Since the tubes have been successful in France, the device should be extended to England. B45 is obviously suitable for the work. A submarine will sink letters for the Embassy in Madrid and a parcel of the tubes between the twenty-seventh and the thirtieth of July, within Spanish territorial waters off the Cabo de Cabron. A green light will be shown in three short flashes from the sea and it should be answered from the shore by a red and a white and two reds."
Hillyard leaned back in his chair.
"B45," he cried in exasperation. "We get no nearer to him."
"Wait a bit!" Fairbairn interposed. "We are a deal nearer to him through Zimmermann's very letter here. What are these tubes which have been so successful in France? Once we get hold of them and understand them and know what end they are to serve, we may get an idea of the kind of man obviously suitable for handling them."
"Like B45," said Hillyard.
"Yes! The search will be narrowed to one kind of man. Oh, we shall be much nearer, if only we get the tubes—if only the Germans in Madrid don't guess this letter's gone astray to us."
Hillyard had reflected already upon that contingency.
"But why should they? The sleeping-car man is held incomunicado. There is no reason why they should know anything about this letter at all, if we lay our plans carefully."
He folded up the letter and locked it away in the drawer. He looked for a while out of the window of the saloon. The yacht had rounded the Cabo San Antonio. It was still the forenoon.