pite Saranoff's words, it must be possible to trace him. He is
undoubtedly releasing his energy from some form of subterranean borer,
and such a thing can be located. The energy he uses must set up
electrical disturbances which instruments will detect. I have had work
started on a number of ultra-sensitive wave detectors which will
record any wave-length from zero to five millimeters. We'll send them
to various points along the seacoast. They ought to pick up the stray
waves from the energy he is using to blast a path through the earth.
I'm not going to bother with the waves from his motor; they may be of
any wave-length, and there would be constant false alarms. I have
another idea."

"What is it?"

"I am judging Saranoff from his previous actions. You remember that he
used a submarine in that alien-smuggling scheme the Coast Guard broke
up, and also when he loosed that sea monster on the Atlantic shipping?
He seems to be rather fond of submarines."

"Well?"

* * * * *

"The amount of energy he uses must be almost inconceivable," Dr. Bird
went on. "He can hardly carry an amount of fuel which will enable him
to bore underground for very many miles, Charleston is on the coast. I
have an idea that he uses a submarine to transport his borer from
point to point. After using the borer he must return to the submarine
for recharging and transportation to the point where he plans to
strike next. I already have two hundred planes scouring the sea
looking for such a craft."

"Where do you expect him to strike next?"

"I have no idea. New York and Washington will undoubtedly be targets
eventually, but neither of them may be next. Meanwhile, would you like
to do a little more flying?"

"Surely."

"A plane is waiting for us at Langley Field. I want to look over the
coast in the vicinity of Charleston Harbor and some of the sounds near
there. If he is using a sub, he must have a base somewhere."

* * * * *

With a competent pilot at the stick, Carnes and the Doctor spent the
day in exploring. The day yielded no results, and with the coming of
dusk they landed at Savannah for the night. Carnes talked with Bolton
over the telephone, but the secret service chief could report no
favorable progress. Tired and disgusted, they retired early, but they
were not destined to enjoy a night of uninterrupted sleep. At one
o'clock a telegram was brought to their room. Dr.