Then near the end of the second hour something happened that abruptly sent a thrill of excitement through the entire expedition. Layroh had just set his apparatus up on a small sand dune beside the trail. The mechanism looked somewhat like a portable radio, with two slender parallel rods on top and a number of dials on the main panel. Layroh swung the rods slowly around the horizon while he carefully tuned the various dials. It was when the rods pointed toward the southeast that there suddenly came the first response he had ever received. From somewhere within the mechanism there came a faint staccato ripple of clear beauty like countless tiny hammers beating upon a crystal gong. * * * * * The sound galvanized Layroh into the nearest approach to emotion anyone had ever seen him display. The giant moved with the furious speed of a madman as he returned the apparatus to the sedan and swung the car out across the sand toward the southeast. After a mile he stopped and hurriedly set the apparatus up again. This time the crystalline signal came in with a noticeable increase in volume. From then on the progress of the party became a mad dash that taxed the endurance of everyone except Layroh himself. After the first hour they entered a terrain so rugged that the cars had to be abandoned and they fought their way forward on foot. Layroh was forced to turn the radiolike apparatus over to one of the men, while he himself carried another mechanism that consisted of a heavy silver cylinder with four flexible nozzles emerging from one end. They held as rigidly as possible to a straight line toward the southeast, scrambling over whatever obstacles intervened. Their only stops were at regular intervals when Layroh checked their course. Each time the crystalline signal came in with greater volume. Their objective appeared to be a cone-shaped peak several miles ahead that loomed up high above the surrounding rock masses. The oddly shaped mountain was identified by one of the men who had once been a Mojave desert rat. "Lodestone Peak," he announced succinctly. "Full of iron, or somethin'. A compass always goes haywire within a radius of ten miles of it." * * * * * It was early afternoon when they finally arrived at a level area at the base of the mountain. For the last two miles Layroh had not stopped long enough to make any tests. Now he set the radiolike apparatus in place some ten yards from the face of a sheer cliff that towered high above them.