at that cave where the stolen freight was
stored," said Sam one day. "Supposing we drive to it?"

"That will suit me," answered Dick. "I want to learn about something
else--that red tin box I saw hanging from a tree."

"Oh, yes, I had forgotten about that," put in Tom. "Well, shall we walk
or drive over?"

It was decided to drive as far as the cave, and not knowing how long
they would be gone, the boys took a lunch along.

"Now, take care of yourselves," warned Randolph Rover. "Don't fall into
any more holes."

"We'll try to watch out!" sang out Tom.

Then Dick cracked the whip, and off the team started at a good pace, the
eldest Rover, however, holding them well under control. It was a clear
and beautiful day. The boys did not dream of the odd adventure in store
for them.

CHAPTER VII

A STRANGE LETTER BOX

"It won't be long now before we'll have to get back to Putnam Hall,"
observed Sam, as they drove along. "Dear old school! How I love it!"

"It's too bad that we are getting too old to go there," said Tom. "But
we can't be boys always."

"I shall be glad to see the other fellows again," came from Dick.

"Do you know what I think?" declared Tom. "I think the Putnam Hall
cadets are the finest lot of boys in the world!"

"Throwing bouquets at yourself, Tom?" said Sam, with a laugh.

"Well, don't you agree with me?"

"I certainly do, Sam, and Captain Putnam is the best teacher in the
world. My, but won't we have fun when we get back!"

"We'll have to have a feast in honor of our return," said Dick, and
smiled that quiet smile of his which meant so much.

The distance to the cave was soon covered, and the boys tied their team
to a tree in that vicinity. They went inside and found that everything,
even to the empty boxes, had been taken away. The place had been
explored by a number of curiosity seekers.

"It is queer that this cave wasn't discovered before," was Dick's
comment, after they had spent half an hour in walking around.

"Perhaps the opening to the road wasn't so large formerly," suggested
Tom. "Dangler may have enlarged it, so he could drive in."

"That is true. Well, it will be a regular picnic place after this. Its
fame will spread for miles around." And Dick was right, and the cave is
a well-known spot in that portion of New York state to this day.

The boys had brought with them two electric pocket lights, as they are
called--lights they had purchased while on their river o