hich the two boys rode reduced its
speed abruptly. Frank cut down the gait of his own craft and they
continued on their way more slowly.

"Nearing our destination, wherever that is," muttered Jack.

The lad felt of his revolvers to make sure that they were ready in case
of an emergency.

"Land ahead," said Frank, suddenly.

Jack gazed straight before him. There, what appeared to be many miles
away, though in reality it was but a few, was a dark blur below.
Occasionally what appeared to be little stars twinkled there. Jack knew
they were the lights of some town.

"Guess that's where we are headed for, all right," he told himself.

Behind the British hydroplane the other German airships came rapidly,
keeping some distance apart, however. Jack leaned close to Frank.

"Just do as the ones ahead of you do," he said quietly. "I don't know
where we are nor what is likely to happen. Keep your nerve and we'll be
all right."

"Don't worry about me," responded Frank. "I'm having the time of my
life."

Jack smiled to himself, for he knew that Frank was telling the truth.
There was nothing the lad liked better than to be engaged in a
dangerous piece of work and more than once his fondness for excitement
had almost ended disastrously.

"Frank's all right if he can just keep his head," muttered Jack. "I'm
likely to have to hold him in check a bit, though."

They had approached the shore close enough now to perceive that the
distant lights betokened a large town.

"Probably Ostend," Jack told himself, "though why they should come this
way is too deep for me."

But Jack was wrong, as he learned a short time later.

The town that they now were approaching was the French port of Calais
and it was still held by the French despite determined efforts of the
Germans at one time or another to extend their lines that far. The
capture of Calais by the Germans would have been a severe blow to
England, for with the French seaport in their possession, the Germans,
with their great guns, would have been able to command the English
channel and a considerable portion of the North Sea coast.

When it appeared that the German aircraft would fly directly over the
city, the leading machine suddenly swerved to the east. The others
followed suit.

The night was very dark, and in spite of the occasional searchlight
that was flashed into the air by the French in Calais, the Teuton
machines so far had been undiscovered. Now, hanging low ov