“How do you make that out?” came from Dick.

“He’ll probably know how to handle him,” supplemented Tom.

“Yes, he would if he’s a bull-fighter,” scoffed Dick, “and I never heard of there being any matadors in the vicinity of Nestorville.”

“Lots of doormats, though,” grinned Tom.

“Say, if you do 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 him.  The man was good-natured, or perhaps he rather liked the idea of a ride in such a novel-looking car.  Anyhow, he called three of his hands and told them to get pitchforks.