his ears, the note of the turbine, low at first, but gradually
rising like the scream of a siren, and the floor of the Ring beneath his
feet throbbed with the vibration.

Bennie forgot the dynamometer, forgot his message to Burke, was
conscious only that he had wakened a sleeping volcano. Then came the
crack of the sparks, and the room seemed filled with the glare of the
blue lightning, for Atterbury, with his telephones at his ears, staring
through his yellow glasses, was sending out the call for the Naval
Observatory.

"NAA--NAA--P--A--X."

Over and over again he sent the call, while in the meantime the
condenser built up its charge from the overflow of current from the
turbine generator. Then the electrician opened a switch, and the roar
outside diminished and finally ceased.

"We can't listen--with the tractor running," he fretted. "The
static--from the discharge--would tear--our detector--to pieces." He
threw in the receiving instrument. For a few moments the telephones
spoke only the whisperings of the arctic aurora, and then suddenly the
faint cry of the answering spark was heard. Bennie watched the words as
the electrician's pencil scrawled along on the paper.

"Waiting for you. Why don't you send? N.A.A."

"They must have--called us before--while the discharge--was running
down," muttered Atterbury. "I think we can send--with the
condenser--now."

He picked up the scrap of yellow paper, read it over, and threw out into
space the message which he did not understand.

"O. K. Wait. Thornton," came in reply.

Two hours later came a second message:

"P--A--X. Burke starts at daybreak. Expects reach you by nine P. M.
Asks you to show large beacon fire if possible.

"THORNTON, N. A. A."

"Hurrah!" cried Bennie. "Good for Burke! Atterbury, we're saved--saved,
do you hear! Go to bed now and don't ask any questions. And say, before
you go see if you can find me a glass of brandy."

* * * * *

It was decided that Burke must land on the plateau above the cliff, and
here the material for the fire was collected. There was little enough of
it and it was hard work carrying the oil up the steep trail. At times
Bennie was almost in despair.

"It won't burn half an hour," said he, surveying the pile. "And we ought
to be able to keep it going all night. There's plenty of stuff in the
valley, but we can't have him come down there, with the tower, the
antennae, a