resting to attending the ball game, even though she loved to be with
the others.

"There goes another building!" yelled Andy Rover, as another report
rent the air. Then those who were looking down the river and across
the lake saw some strange objects being hurled through the sky in the
direction of Clearwater Hall.

"If that whole ammunition factory starts to go up, it will certainly
mean damage to the boarding school," declared Jack. "I guess the best
we can do is to get down there and see if Mary is safe."

"That's just what I say!" declared Fred. "I'm going to get down there
just as fast as I can." And he ran off, to board one of the
automobiles headed in that direction.

Now, I know it will not be at all necessary to introduce the Rover
boys or their friends to my old readers, but for the benefit of those
who have not perused any of my former stories a few words concerning
these characters will be necessary. In the first volume, entitled "The
Rover Boys at School," I told how three brothers, Dick, Tom, and Sam
Rover, were sent off to Putnam Hall Military Academy, where they made
a great number of friends, including a youth named Lawrence Colby.
From Putnam Hall the lads went to Brill College, and on leaving that
institution of learning went into business in New York City with
offices on Wall Street. They organized The Rover Company, of which
Dick was now president, Tom secretary and general manager, and Sam
treasurer.

While at Putnam Hall the three Rovers had become acquainted with three
very charming girls, Dora Stanhope and her two cousins, Nellie and
Grace Laning, and when Dick went into business he made Dora Stanhope
his lifelong partner. A short time later Tom married Nellie Laning and
Sam married Grace.

The three brothers purchased a fine plot of ground on Riverside Drive
overlooking the noble Hudson River, and there they built three
connecting houses, Dick and his family living in the middle house,
with Tom on one side and Sam on the other.

About a year after their marriage Dick and his wife became the proud
parents of a little son, who was named John after Mr. Laning. This son
was followed by a daughter, called Martha after her great-aunt Martha
of Valley Brook Farm, where the older Rovers had spent many of their
younger days. Little Jack, as he was commonly called, was a manly lad
with many of the qualities which had made his father so well liked and
so successful.

It was about this time th