had
been started in the far north and had spread out over the earth with the
velocity of sound. Though the barographs themselves gave no indication
whence this wave had come, the variation in its intensity at different
meteorological observatories could be accounted for by the law of
inverse squares on the supposition that the explosion which started the
wave had occurred at fifty-five degrees north, seventy-five degrees
west."

The professor paused and wiped his glasses. With a roar a Taube slid off
the landing stage, shot over toward the hangars, and soared upward.

"Is that all?" inquired the general, turning again to the chart.

"That is all, your Excellency," answered Von Schwenitz.

"Then you may go!" muttered the Imperial Commissioner. "If we find the
source of these disturbances where you predict you will receive the
Black Eagle."

"Oh, your Excellency!" protested the professor, his face shining with
satisfaction.

"And if we do _not_ find it--there will be a vacancy on the faculty of
the Imperial University!" he added grimly. "Good afternoon."

He pressed a button and the departing scholar was met by an orderly and
escorted from the War Bureau, while the adjutant joined Von Helmuth.

"He's got him! I'm satisfied!" remarked the Commissioner. "Now outline
your plan."

The bullet-headed man took up the calipers and indicated a spot on the
coast of Labrador:

"Our expedition will land, subject to your approval, at Hamilton Inlet,
using the town of Rigolet as a base. By availing ourselves of the
Nascopee River and the lakes through which it flows, we can easily
penetrate to the highland where the inventor of the Ring machine has
located himself. The auxiliary brigantine _Sea Fox_ is lying now under
American colours at Amsterdam, and as she can steam fifteen knots an
hour she should reach the Inlet in about ten days, passing to the north
of the Orkneys."

"What force have you in mind?" inquired Von Helmuth, his cold gray eyes
narrowing.

"Three full companies of sappers and miners, ten mountain howitzers, a
field battery, fifty rapid-fire standing rifles, and a complete outfit
for throwing lyddite. Of course we shall rely principally on high
explosives if it becomes necessary to use force, but what we want is a
hostage who may later become an ally."

"Yes, of course," said the general with a laugh. "This is a scientific,
not a military, expedition."

"I have asked Lieutenant Muenster to report upo