ng
mules to board the transport for Europe.

The boys hurdled over piles of food and ammunition, wended their way
through scores of stacks of ordnance, and finally over a gang-plank to
the vessel. There they saluted and reported to the officer of the day,
who directed them to go at once to the wireless room.

As they entered there Lieutenant Mackinson was busily engaged in "tuning
up" his instruments. He stopped when he saw them and reached into an
inner pocket, from which he produced three large oblong envelopes. One
was addressed to each lad, and as they accepted them they saw that each
was closed to prying eyes by the official seal of Uncle Sam.

Swept by various emotions, the boys stood there gazing first at the
envelopes and then at Lieutenant Mackinson.

"Well," said the lieutenant at last, with an amused smile, "do you want
me to retire while you read your communications?"

"Oh, no, not at all, sir," Joe hastened to say, and as if to prove the
statement all three envelopes were ripped open and the single sheet of
paper in each drawn forth.

Especially addressed to each lad, the letters were identical and read:

"I hereby convey to you my heartiest congratulations upon the
efficient and heroic manner in which you and your two friends
discovered and frustrated a plot to conceal enemy ammunition in the
vicinity of this naval base. You all displayed true American
courage; and I wish you every success for the future."

The letters were signed by the commandant of the Philadelphia Navy Yard.

"Look at that," said Slim, pushing his letter at Lieutenant Mackinson,
utterly forgetful of the fact that the other man was his superior
officer. "Ain't--isn't that fine, though? For the commandant to mention
it that way, I mean."

"Yes," admitted Lieutenant Mackinson, "but he wouldn't have mentioned
it that way if you hadn't deserved it."

"I'm not going to lose that letter," announced Jerry.

"Nor I," added Joe, "although we only did what any other fellows would
have done under the same circumstances."

"Well," said Lieutenant Mackinson, "it showed that you were to be
depended upon in an emergency, and emergencies are likely to crop up at
any time in our work, so let's get down to business."

He immediately began explaining the apparatus of the wireless room--how
messages were sent and received; the power of the batteries and their
auxiliaries; the switch-board regulating voltage; the aut