t suddenly of a reply. He rushed into the charthouse, to
return in a moment with a lighted lantern and a copy of the _Nautical
Almanac_ which would serve to hide the flame between flashes. He
flashed an answer.

Again the pale light flickered from the dark mass of land, spelling
words out rather slowly, as if the sender were uncertain in his
knowledge of Morse. Surprised as Dan had been by the signal from an
island marked on the charts as uninhabited, he was astonished at the
message that now came to him.

"You are in terrible danger," he read in the flashes. "Dreadful thing
here. Hurry away. Radio for warships. I am--"

The winking light suddenly went out. Dan strained his eyes to watch
the point where it had been, and a few seconds later he saw a curious
thing. A darting, stabbing lance of green fire flashed out across the
barren, rocky cliff, lighting it fleetingly with pale green radiance.
It leapt out and was gone in an instant, leaving the shoulder of the
island dark as before.

Dan watched for long minutes, but he saw nothing more brilliant than
the pale gleam of phosphorescence where the waves dashed against the
sheer granite wall of the island.

"What you t'ank?" Larsen broke in upon him.

* * * * *

Dan started, then answered slowly. "I don't know. First I thought
there must be a lunatic at large. But that green light! I didn't like
it."

He stared again at the looming mass of the island. Davis Island is one
of the innumerable tiny islets that dot the South Pacific; merely the
summit of a dead volcano, projecting above the sea. Nominally claimed
by Great Britain, it is marked on the charts as uninhabited.

"Radio for warships, eh?" he muttered. A wireless transmitter was one
of many modern innovations that the _Virginia_ did not boast. She had
been gathering copra and shell among the islands long before such
things came into common use, though Dan had invested his modest
savings in her only a year before.

"What would anyone want with warships on Davis Island?" The name
roused a vague memory. "Davis Island?" he repeated, staring in
concentration at the black sea. "Of course!" It came to him suddenly.
A newspaper article that he had read five years before, at about the
time he had abandoned college in the middle of his junior year, to
follow the call of adventure.

The account had dealt with an eclipse of the sun, visible only from
certain points on the Pacific. One