etailed to remain in Chatham with the American submarine. It
was to undergo extensive repairs after its perilous adventure on the
bottom of the sea.

"And now I have a surprise for you," smiled "Little Mack," as he took
from his inner pocket an official-looking envelope and handed it to
Jack. The latter took the proffered envelope and tore it open. What
he read therein was enough to make any ambitious young American
submarine sailor open his eyes.

It was an official order announcing the appointment of Jack as an
ensign with an assignment to the captured U-boat as executive officer
under Lieutenant-commander McClure!

Jack could scarce believe what he read and was so dumbfounded he could
not speak for some minutes.

"And our friend Wainwright is to be with us, too," continued McClure.

"You mean Ted Wainwright?" asked Jack.

"Yes, he will be my aide and relieve the wireless operator at times,"
explained "Little Mack." "As a matter of fact," he continued, "I will
ship the most of my old crew on the U-boat. The _Dewey_ will be out
of service for some time and Cleary will probably take her out on her
next voyage with a brand new crew."

Jack excused himself in a few minutes to hurry away and acquaint Ted
with the news. He found his chum writing letters and broke the news
to him. The two did a fine young hornpipe dance, so delighted were
they over the fact that they had been assigned together to the same
vessel again---and to the famous U-boat.

The next ten days were taken up by the new officers of the U-boat
in acquainting themselves thoroughly with the operation of the captured
craft, and in preparations for the new trip to sea. Latest news from
the front had shown the Allies closing in on the German naval bases
along the North Sea front. The combined armies of the Americans,
the French and the British under one commander had driven the Huns
northward till Zeebrugge was in danger of being wrested from them.
Consequently, the American lads were anxious to get into the fray with
their powerful new vessel.

"What are they going to call our new Kaiser-buster?" asked Jack of his
chief one morning while they were inspecting the ship's storage tanks.

"So far as the Germans are concerned she is still the U-91," said
the little captain. "You notice that we haven't changed the outside
dress of her a single bit. Unless I lose my guess we are going to
get pretty close to the Boche with this old boat of theirs