Meanwhile Ingra, with the evident intention of concealing the movements of the vessel, dropped her so low that we hardly skipped the tops of the trees that we were passing over, for now we had entered a wide region of unbroken forest. Still that black dot followed straight in our wake, and I easily persuaded myself that it was yet growing larger. Edmund declared that I was right, and expressed his surprise, for we were now flying at the greatest speed that could be coaxed out of the motors. Suddenly a shocking thought crossed my mind. I tried to banish it, fearing that Ingra might read it in my eyes, and act upon it. Suppose that he should hurl us overboard! It was in his power to do so, and it seemed a quick and final solution. But he showed no intention to do anything of the kind. He may have had good reasons for refraining, but, at the time I could only ascribe his failure to take a summary way out of his difficulty to a protecting hand which guarded us even in this extremity. On we rushed through the humming air, and still the pursuing speck chased us. And minute by minute it became more distinct against the background of the great cloud dome. Presently Edmund called our attention to something ahead. "There," he said, "is Ingra's hope and our despair." I turned my head and saw that in front the sky was very dark. Vast clouds seemed to be rolling up and obscuring the dome. Already there was a twilight gloom gathering about us. "This," said Edmund, "is apparently the edge of what we may call the temperate zone, which must be very narrow, surrounding in a circle the great central region that lies under the almost vertical sun. The clouds ahead indicate the location of a belt of contending air currents, resembling that which we crossed after floating out of the crystal mountains. Having entered them, we shall be behind a curtain where our enemy can work his will with us." Was it knowledge of this fact which had restrained Ingra from throwing us overboard? Was he meditating for us a more dreadful fate? It was, indeed, a land of shadow which we now began to enter, and we could see that ahead of us the general inclination of the ground was downward. I eagerly glanced back to see if the pursuers were yet in sight. Yes! There was the speck, grown so large now that there could be no doubt that it was an air ship, driven at its highest speed. But we had entered so far under the curtain that the greater part of the dome was concealed, the inky clouds hanging like a penthouse roof far behind. We could plainly perceive the chasers; but could they see us? I tried to hope that they could, but reason was against it. Still they were evidently holding the course.