that again I'll throw you out of the car," cried Jack
at this atrocious pun.

"Sorry, couldn't help it. Just slipped out," said Tom contritely.

"Well, you'll slip out if the offense is repeated," retorted Dick.
"But," he went on, "seriously, fellows, we've got to do something."

"Try blowing the horn," suggested Tom. "It has scared everything else
we met. Horses shy at it, so do other autos. Maybe it will get the
bull's goat."

"I'll try it, at all events," said Jack.

He pressed the button and the unearthly screech of the electric auto's
siren split the air. But the bull merely cast an inquiring glance in
their direction and then resumed his vigil over the professor.

"Boys," wailed the unhappy geologist, "can't you do something,
anything? I can't roost in this tree all night, like a bird."

The boys couldn't help grinning at this. With his sharp nose, big
spectacles and flapping black garments, the professor did look like a
mammoth black crow.

"Reminds me of the fox and the crow," said Dick, in a low voice, to
his companions.

"Only, in this case, the fox is a bull, and the piece of cheese is the
bag of specimens," added Tom.

They looked about helplessly. There was no farmhouse in sight and the
road did not appear to be much traveled.

"We'll have to go for help," declared Jack.

"The only thing to do," agreed Tom.

The professor was hailed. He had climbed to another limb with infinite
difficulty, because of the encumbering bag of rocks on his back. He
declared that he could manage to get along till the boys came back.

"By a merciful provision of providence," he said whimsically, "bulls
can't climb trees. The situation might be worse if it was a bear."

"It would be unbearable," declared Dick to Tom.

"But just the same there's trouble a brewin'," retorted Tom. "I wish
that farmer would show up."

"As I said before--I don't," responded Jack, as he prepared to start
off.

"Why?"

For answer Jack waved an eloquent hand toward the gap in the stone
fence.

"I guess he wouldn't be best pleased to find that his fence had been
torn down," explained Jack, as the car drove off, leaving the
professor marooned in his tree with the sentinel bull waiting
patiently below.

Some distance down the road the boys came to a farmhouse. Several men
were working in the field under the direction of a stout, red-faced
man. Jack shouted to them, and when the red-faced man came up he
explained the situation to