up the Dardanelles, and passed through the Kiel canal."

"And when you stop to think of it, we're pretty lucky to be here right
now," returned Jack dryly.

"Well, so we are, if that's the way you look at it. However, I wouldn't
mind having another such chance."

"You'll probably get it."

Conversation lagged as the boys took in the scenes about them; and there
was little more talk during the trip. They stopped more than once, and,
loitering along, it was dark when they neared their destination.

As they would have drawn up to the wharf there was a sudden flash of
light--gone in a moment--followed by a dark body that swished by them
like a flash.

Frank uttered an exclamation of astonishment.

"See that?" he demanded.

"Yes. What could it have been?"

"You've got me, but it's heading toward the open sea. Great Scott! Maybe
it's an enemy."

"An enemy?"

"Yes; you know how anxious the Germans are over this submarine business.