e passing, and
yet there was none due now, for Mr. Nestor had just left one, and
another would not arrive for an hour.

"That's queer," mused Mary's father. "If I didn't know to the contrary,
I'd say that sounded like heavy guns being fired from a distance, or
else blasting. It seems to come from the Swift place," he went on. "I
wonder what they're up to in there."

Suddenly the rumbling became more pronounced, and mingled with it, in
the dusk of the evening, were the shouts of men.

"Look out!" some one cried. "She's going for the fence!"

A second later there was a cracking and straining of boards, and the
fence near Mr. Nestor bulged out as though something big, powerful and
mighty were pressing it from the inner side.

But the fence held, or else the pressure was removed, for the bulge
went back into place, though some of the boards were splintered.

"Have to patch that up in the morning," called another voice, and Mr.
Nestor recognized it as that of Tom Swift.

"What queer doings are going on here?" mused Mary's father. "Have they
got a wild bull shut up in there, and is he trying to get out? Lucky
for me he didn't," and he hurried on, the rumbling noise become fainter
until it died away altogether.

That night, after his supper and while reading the paper and smoking a
cigar, Mr. Nestor spoke to his daughter.

"Mary, have you seen anything of Tom Swift lately?"

"Why, yes, Father. He was over for a little while the other night, but
he didn't stay long. Why do you ask?"

"Oh, nothing special. I just came past his place and I heard some queer
noises, that's all. He's up to some more of his tricks, I guess. Has be
enlisted yet?"

"No.

"Is he going to?"

"I don't know," and Mary seemed a bit put out by this simple question.
"What do you mean by his tricks?" she asked, and a close observer might
have thought she was anxious to get away from the subject of Tom's
enlistment.

"Oh, like that one when he sent you something in a box labeled
'dynamite,' and gave us all a scare. You can't tell what Tom Swift is
going to do next. He's up to something now, I'll wager, and I don't
believe any good will come of it."

"You didn't think so after he sent his wireless message, and saved us
from Earthquake Island," said Mary, smiling.

"Hum! Well, that was different," snapped Mr. Nestor. "This time I'm
sure he's up to some nonsense! The idea of crashing down a fence! Why
doesn't he enlist like the other chaps,