Hamerton, of course, was ignorant of this highly-confidential test, but the unusual sight of a pole projecting far in the wake of the seaplanes attracted his attention. At first he came to the conclusion that it was a form of aerial torpedo tube, till it suddenly occurred to him that it might be a form of arresting the attraction of gravity in the event of an accidental downward plunge.
Almost as soon as the seaplanes passed out of sight Lieutenant Schaffer entered the room, accompanied by the two men who acted as jailers.
"You haf seen part of our Zherman air fleet?" he enquired affably.
"Yes," replied Hamerton; then, on the spur of the moment, he added: "I see you have adopted the parachute principle in the event of an accident?"
"Mein Gott!" ejaculated the astonished lieutenant; "how you know that?"
"Saw it with my own eyes," replied the Sub, delighted at the successful guess he had made. "I thought your people would collar the idea from us sooner or later."
"Collar? What do you mean?" asked Schaffer, completely mystified. "Collar? That something is around the neck--dog collar, horse collar, stylish collar, hein?"
"Crib? Ach, I haf it! Crib something is to do with children. You say our Zherman air fleet it is in infancy, eh? You are all wrong, as you will see."
"I said nothing of the sort," said Hamerton, smiling. "I said you collared, cribbed our ideas--sneaked them."
"I understand not still," expostulated the German lieutenant. "I haf not learned the word 'sneak' in my vocabulary."
"Then suppose I explain that you borrowed the idea of a parachute from us?"
"You then have a like device in England? Then it is by spies such as you, Herr Smidt, that it was made known."
Whatever had been his object in entering Hamerton's cell the Sub never found out, for the lieutenant lost no time in informing his superior officer that these English had already got to learn how to prevent disasters to aircraft heavier than air.
As Hamerton had foreseen, the gale began to make itself felt. Just before sunset a strong breeze from the east sprang up, and in less than twenty minutes the Sub could see columns of spray dashing high above the seawall between the East Kalbertan Battery and the Düne Fort.