"That's just what I believe has happened," Ashton replied seriously. "We've been watched--as I suspected we were." "You've said so all along, I know." "And now I'm quite convinced of it. And whoever has watched us making our experiments now knows that to-night our efforts have been crowned with success." "Well," I remarked after a pause. "If what you say is true, Teddy, we shall have to be very wary in future. I know there are a great many unscrupulous persons who would be ready to go to any length in order to learn this secret discovery of ours which, when fully developed, will, I feel convinced, mean the buckling-up of the Zeppelin menace." "That's quite true, Claude," Roseye declared. "At Hendon and elsewhere there are, I know, a number of men intensely jealous of your success, and of the one or two ideas which you have patented, and which are now adopted in the construction of our military aeroplanes." "It's really astonishing how many enemies one makes quite unintentionally!" declared Teddy, leaning against the bench. "Claude has more than I have, I believe--and I never disguise from myself that I've got a really fine crop." "Only the other day, when Lionel dined with us, he was speaking to dad about spies," Roseye said. "He told us that he felt sure that we had men in our air-service who sent every new development and idea to Germany. Do you think that's really a fact?" "A fact!" I echoed. "Why, dearest, of course it is! We've seen the result of it many times. As soon as we had that integral propeller the Germans knew, and copied us; the secret of Jack Pardon's new dope was known in a few days, and the enemy are using it on every one of their machines to-day. Nothing is secret from those brutes." "But who does all this?" asked Roseye. "Why, what I call the Invisible Hand," was my reply. "The Invisible Hand was established in our midst in about 1906, when the Kaiser sat down and craftily prepared for war. He saw himself faced by the problem of the great British power and patriotism, and knew that the Briton would fight every inch for his liberty. Therefore the All-Highest Hun-- the man who will be held up to universal damnation for all time-- proceeded to adopt towards us the principle of dry-rot in wood. He started a system of sending slowly, but very surely, his insect-sycophants to burrow into the beam of good British oak which had hitherto supported our nation. That beam, to-day, is riddled by these Teutonic worms--insects which, like the book-worm, are never seen, yet, directed by the Invisible Hand, are only known by their works." "Then you think there really are spies at Hendon?" "Of that I'm quite certain," was my reply. "We all know that there are spies at every aerodrome--while in the higher ranks those who control our air-services, though patriotic enough, seem to suffer by reason of the still higher control which divides responsibility."