the boys ordered a new engine for the _Dartaway_, one
which would make sailing safer, especially in a stiff wind. The makers
said they would send the new engine immediately, and a machinist to
install it, and they agreed to take the old engine back at cost price,
since it was practically new.

It must not be supposed that the Rover boys neglected their studies. As
my old readers know, whatever they tackled they went at with all their
might, and this applied to their work as well as their play.

"Dad sent us here to get an education," said Dick. "And while I am here
I am going to study all I can. There is no telling how long I'll be able
to remain here anyway."

"Thinking of dad's western affairs?" asked Sam.

"Yes; I may have to take hold and help him and Uncle Randolph out. Both
of them are not as young as they used to be, you know."

"That's true, Dick. I noticed dad's hair getting pretty gray, and
uncle's is almost white."

The boys had written home and also to the Stanhopes and the Lanings, and
soon came letters in return. One, from Mr. Anderson Rover, was of
special importance.

"I have news out of the ordinary," wrote the parent. "That
man Crabtree and Tad Sobber have come back to the old mill. I
got the word from Peter Marley. He says they act very
suspiciously, and that a boy who works for him overheard
Crabtree and Sobber talking about us. I have sent for a
detective to come out from the city and watch them for a
while. If anything new develops I will let you know."

"Now what in the world can old Crabtree and Sobber be up to?" asked Sam,
after all had read the communication.

"Up to some trick, I'll bet a new hat," declared Tom. "I am glad dad
sent for the detective. I hope he catches them red-handed at something,
and locks them up."

"They certainly ought to be locked up," was Dick's comment.

The boys studied hard that evening and by ten o'clock all were tired out
and ready to go to bed. But, just as they were on the point of retiring,
there came a knock on the door of the room occupied by Tom and Sam, and
Stanley appeared.

"You are wanted in Room 14!" said the student, in a loud whisper. "Come
right along."

"What's up?" asked both boys.

"Feast--ice-cream and cake. Max and Spud were down to the town and they
brought the stuff along. Come on, before it's too late and the ice-cream
melts."

"Me for the ice-cream!" cried Tom, and did a handspring over h