Suddenly my attention was arrested by a crystal clashing sound. There was a marching rhythm in it, and the clatter of weapons. I crouched down the shrubbery and peered fearfully about. I saw a line of men, queerly equipped soldiers, marching in single file over the nearest knoll. They seemed to be wearing a closely fitting chain mail of silvery metal, and they had helmets, breastplates and shields that threw off the sunlight in scintillant flashes of red, as if made of rubies. And their long swords flashed like diamonds. Their crystal armor tinkled as they came, in time to their marching feet. One, whom I took to be the leader, boomed out an order in a hearty, mellow voice. They passed straight by, within fifty yards of me. I saw that they were tall men, of magnificent physique, white-skinned, with blond hair and blue eyes. On they went, in the direction of the fire-topped mountain, until they passed out of sight in a slight declivity, and the music died away. It is needless to say that I was excited as by nothing that I had seen before. A race of fair-haired men in an Australian valley. What a sensational discovery! I supposed that they had built the metal ladder and come down it into the valley, but from whence had they come? Or was the Mountain of the Moon itself the cradle of humanity, the Garden of Eden? Then the crystal weapons of the soldiery suggested that they used some transparent crystalline substance in lieu of metal, and that the iridescent crown upon the mountain might be the city of the race. Was it Austen's "crystal city?" That would suggest a high civilization, but I saw no sign of the mechanical devices that are the outstanding features of our own civilized achievement. Certainly the soldiers had carried no modern weapons. Then I thought of the footprints and the eerie laugh. I wondered what contact Austen had had with these people. Had they been friends or foes? I wondered if it had been the men of the crystal city who had paid me a visit outside the cliffs. If so, the red torpedo-shapes of the night must be aircraft, and they must have advanced the art of aerial navigation to a very high degree. I determined, first of all, to do some spying, and find out as much as possible about the strange race before I revealed my presence. I was not in a very good trim for battle, and I had taken much pains for concealment when the men passed. But I had little doubt that my guns were so far superior to their crystal swords that I could fight them at any odds if they proved unfriendly.