“That is because you lack imagination, doctor, or you would picture to yourself my contrivance in full swing on the lawn in front of Wedwell Hall.”

“God forbid that I should witness such a scene!”

“Simply because you fail, Peters, to see in your mind’s eye the merit of the invention. Can’t you imagine an enormous cross-bow, with two large grooves in the stock for the air-ship to slide up when the bow is bent and the trigger pulled?”

“No, I don’t see it.”

“You will presently when I further explain that these grooves will be three feet apart, and that the car or sledge of the air-craft will slide up these grooves, as two half round pieces of wood will be fastened at the bottom of the sledge. Of course the wire cord of the great steel bow will be drawn down and fixed behind the air machine before the trigger is pulled.”

“And how long after this bit of trigger-nometry do you expect to be alive, man?”

“Oh, that will be all right; you will see soon how the thing will work.”

“Never, I fear.”

“Well, I’ll try to make you, anyhow; and don’t forget, doctor, that the craft or cruiser (call it which you like) will narrow at the stem.”

“What for, Mr Falcon?”