r man's need of silence, but his
curiosity could not be longer restrained.

"What's back of it all?" he demanded. "What caused it? The shock was
like no earthquake I've ever known. And this tidal wave--" He was
reaching for a small switch. He turned a dial to the words: "News
Service--General," and the instrument broke into hurried speech.

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 re