"I'm going to trust you with a secret which, if you blab, will get me into a big row."
"Very good, sir. I shan't talk, you know that, sir."
"Well, I have promised a great friend at home to give him a flight, and I'm going to take him up to-day in your place—only as it is strictly against the Royal Flying Corps regulations to take anyone on a Corps machine, you must play up and not give the show away."
"Trust me for that, sir."
"My friend knows that he is to take your place—that is why I've put in a second suit of clothes—and he has asked me to give you a fiver."
"Very much obliged, I am sure, sir."
"All right. That is why I told you to put a suit of your own uniform in my bag. My friend will put on your uniform and will take your place. You will have to be careful not to be seen in Plymouth till he has changed at the hotel. I shall drop you at Exeter and you must go on to Plymouth by train; take two rooms for me at the 'Duke of Cornwall,' which is right against the station, and then hang about the place till I arrive. If anyone questions you—which is unlikely—you must only say that you are my mechanic from Salisbury. But don't you go near Crownhill Barracks till after we have arrived; then you may go to the canteen and 'gas' as much about the flight as you like."
"Very good, sir; I quite understand. I'll slip off quietly at Exeter so as not to be noticed."
For the next hour the steady hum of the great propeller was the only sound heard by the airmen, but just as Crewkerne had been passed a new note sounded—a steady umph! umph! umph! like the distant throbbing of a drum.
"Jackson, do you hear that?"