It told of earth shocks in many places--the whole world had felt it--some tremendous readjustment among the inner stresses of the earth--most serious on the Atlantic seaboard--the great Harkness Terminals destroyed--some older buildings in the business district shaken down--loss of life not yet computed.... "But what _did_ it?" Chet Bullard was repeating in the cabin of their floating ship. "A tremendous shake-up like that!" Harkness silenced him with a quick gesture of his hand. Another voice had broken in to answer the pilot's question. "The mystery is solved," said the new voice. "This is the Radio-News representative speaking from Calcutta. We are in communication with the Allied Observatories on Mount Everest. At eleven P. M., World Standard Time, Professor Boyle observed a dark body in transit across the moon. According to Boyle, a non-luminous and non-reflecting asteroid has crashed into the earth's gravitational field. A dark moon has joined this celestial grouping, and is now swinging in an orbit about the earth. It is this that has disturbed the balance of internal stresses within the earth--" * * * * * "A dark moon!" Chet Bullard broke in, but again a movement from Harkness silenced his exclamations. Whatever of dull apathy had gripped young Harkness was gone. No thought now of the devastation below them that spelled his financial ruin. Some greater, more gripping idea had now possessed him. The instrument was still speaking: "--Without light of its own, nor does it reflect the sun's light as does our own moon. This phenomenon, as yet, is unexplained. It is nearer than our own moon and smaller, but of tremendous density." Harkness nodded his head quickly at that, and his eyes were alive with an inner enthusiasm not yet expressed in words. "It is believed that the worst is over. More minor shocks may follow, but the cause is known; the mystery is solved. Out from the velvet dark of space has come a small, new world to join us--" The voice ceased. Walter Harkness had opened the switch. "The mystery is solved," Chet Bullard repeated. "Solved?" exclaimed the other from his place at the controls. "Man, it is only begun!" He depressed a lever, and a muffled roar marked their passage to a distant shaft of blue, where he turned the ship on end and shot like a giant shell for the higher air. There was northbound travel at thirty-five, and northward Harkness would go, but he shot straight up. At forty thousand he motioned the master-pilot to take over the helm. "Clear through," he ordered; "up into the liner lanes; then north for our own shop." Nor did he satisfy the curiosity in Chet Bullard's eyes by so much as a word until some hours later when they floated down. * * * * *