docks
unobserved. By a submarine? But _La Liberte_ had lain at anchor in an
enclosed basin; besides there were the outer basins, patrol boats,
sentries, the constant coming and going of sailors and marines, of
launches, of boats of all kinds. How could an enemy creep unobserved
past all these?

True, the accident had occurred at dawn, when every one but the sentries
was asleep. But even at that hour the harbour was strictly guarded. An
enemy, to enter unseen, would have to be impalpable, invisible....

Besides, how could a mine or a torpedo or a submarine have caused the
explosion of the magazines, one after the other, at regular
intervals--"spaced," one of the officers had said, "like the reports of
a heavy gun." First one had been fired, and then a second, and then a
third; Delcasse, closing his eyes, had a vision of a ghostly figure
stealing from one to another, torch in hand....

His mind roved back again over his talk with Lepine. Could it have been
done by wireless? Not the ordinary wireless, but some subtle variant of
ether waves, some new form of radio-activity, which in some way caused
combustion? There was an enemy which could flit unseen from magazine to
magazine, which no locks nor bars could guard against....

His heart faltered at the thought. The possessor of such a secret would
have the world at his mercy. No ship would be safe, no fort, no
artillery-caisson. Armies and navies alike would melt before him,
destroyed by the explosion of their own ammunition. Ah, if France
possessed that secret....

He shook his head impatiently and turned on his side.

"I am dreaming foolish dreams," he told himself. "It is time to sleep."

CHAPTER IV

THE ALLIES AT WORK

It was nearly four o'clock when Crochard, Lepine and Pigot took their
leave of M. Delcasse and made their way through the dark and silent
streets in the direction of the Hotel du Nord. The people who had leaped
from their beds at sunrise, wearied at last by the emotions of the day
and dampened by the fine rain which had begun to fall, had gone to bed
again. Only about the harbour were there any signs of life. There the
searchlights of the battleships still played about the wreck, where
squads of marines were searching for the bodies of their comrades.

The three men, their coats buttoned about them, their hats pulled down,
hurried on in silence, each busy with his own thoughts. Crochard and
Lepine were planning the campaign; Pigot had