Jules and Yvette left the next day. Jules’ car was quite an ordinary one, but it had one important detail added. In the hollow flooring was cunningly concealed a small but powerful wireless telegraph set, the power for which was supplied by the engine. It was highly efficient, but had one serious drawback; it could only be used while the car was at rest owing to the necessity for running an aerial wire up some tall structure, such as a building or a tree. This, in a country where every one was specially suspicious of spies, was a serious peril.
Three days later seven mysterious dots began to excite the ungovernable curiosity of the wireless world!
Jules and Yvette, on arrival in Berlin, had taken rooms adjoining one another at the “Adlon,” the big cosmopolitan hotel which is always crowded with visitors from every country under the sun. Yvette posed as a school teacher on an educational tour, but her position was one of great danger. It was impossible to disguise her face, and although she had done what she could to destroy her French individuality by wearing peculiarly hideous German clothes, there was the ever-present danger that she would be seen and recognised by some of the many German agents who during the war had learnt to know her features, and who had good reason to remember her daring exploits in Alsace.
At the same time, in order to have a possible retreat in a humbler neighbourhood, Yvette had hired a room in one of the mean quarters of the town, putting in a few miserable sticks of furniture and giving out that she was a sempstress employed at one of the big shops.
She and Jules had decided never to speak in public. It was essential, however, that they should be able to communicate freely, and through the wall between their rooms Jules had bored with a tiny drill a hole through which he had passed a wire of a small pocket telephone. They could thus talk with ease and with the doors of their rooms locked they were absolutely safe from detection so long as they spoke in a whisper.
It was on a dark night, the sky obscured by heavy masses of clouds, that Dick rose in the Mohawk from the Forest of Fontainebleau and headed for Verdun. A couple of hours’ flying brought him over the fortress and he descended in a clearing in a dense wood where he was welcomed by Captain Le Couteur, the chief engineer of the military wireless station. Covered with big tarpaulins, the Mohawk was left under the guard of a dozen Zouaves, and Dick and Captain Le Couteur motored to the citadel.
Here the Captain took Dick directly into the steel-walled chamber deep under the fortifications which was the brain of the defences of Verdun. It was the nucleus of the entire system of telegraph and telephone wires which, in time of war, would keep the commander of the troops in the district fully informed of everything that was happening in every sector of the defences. The innermost room of all, where none but the Captain himself had access, contained the secret codes which dozens of foreign agents would have willingly risked their lives to possess. Their efforts—and they knew it—would have been in vain, for the chamber was guarded day and night by a band of picked men whose fidelity to France was utterly beyond the possibility of suspicion.
“Your messages have already started—the seven dots at intervals of seven seconds,” said Captain Le Couteur when they were comfortably seated in the innermost room. “I got half a dozen test calls last night and everything seems to be working well. I expect they are arousing some interest, for operators all over Europe will be mystified. There will be another call about nine o’clock and in the meantime you had better get some sleep. I will call you if anything happens.”
Dick stretched himself on a couch and slept peacefully. Nine o’clock found him with Captain Le Couteur seated in the innermost room at a table covered with delicate wireless apparatus. Turning a switch, the Captain lit up the row of little valves, put the receiving set in operation, and assuming one headpiece himself, handed another to Dick.
He placed his hand upon one of the ebonite knobs of the complicated apparatus and slowly turned it. Then he turned a second condenser very carefully.