One day, during the time of repose, I happened to be, with Juba, in our room on that stage of the great tower where the car was anchored, while Edmund and the others were below in the palace. Juba was already asleep, and I was lying down and courting drowsiness, when a slight noise outside attracted my attention. I stepped softly to the door and looked out. The door of the car was open! Supposing that Edmund was there I approached to speak to him. By good fortune I was wearing the soft slippers worn by everybody here, and which we had adopted, so that my footsteps made no sound. As I reached the car door and looked in, I nearly dropped in the intensity of my surprise and consternation. There, at the farther end, was Ingra, on his knees before the mechanical mouths which swallowed the invisible elements of power from the air; and beside him was another, also on his knees, and busy with tools, apparently trying to detach the things. The explanation flashed over my mind; Ingra had brought a skilled engineer to aid him in discovering the secret of the car, and, no doubt, to rob it of its mysterious mechanism. They seemed to fear no interruption, because Ingra had undoubtedly informed himself of the fact that for a day or two past we had abandoned the use of our room in the tower, and taken our repose in our apartments in the palace. It was by mere chance that Juba and I had, on this occasion, remained so long aloft that I had decided to take our sleep in the tower room. Anticipating no surveillance, Ingra was not on his guard, and had no idea that I was behind him. Instinctively I grasped for my pistol but instantly remembered that it was with my coat in the room. I tiptoed back, awoke Juba, making him a sign to be noiseless, got the pistol, and returned, without a sound, to the open door of the car with Juba at my heels. They were yet on their knees, with their heads under the shelf, and I heard the slight grating made by the tool that Ingra's assistant was using. The pistol was in my hand. What should I do? Shoot him down without warning, or trust to the strength of Juba to enable us to overcome them both and make them prisoners?