"And I won't let go of the specimen," declared the professor with equal firmness.
"What on earth are we to do?" said Jack, looking helplessly at Tom.
Not far off Tom had noticed a man digging potatoes. It gave him an idea.
"We can borrow that man's shovel and dig his arm out," he suggested.
"It's about the only thing to do, I guess," said Jack. "You go and see if you can get it. I'll keep the professor company."
Tom soon came back. The potato-digger accompanied him. The man was much interested in the eccentric man's plight.
"If that ain't the beatingest I ever heard on," he remarked, gazing at the professor, and then he tapped his head significantly and looked at the boys in a knowing way.
"Nobody home, eh?" he said with a grin. Fortunately the professor did not hear him; but the boys could hardly keep from laughing outright as they set to work with the spade. A few minutes of brisk digging set the professor at liberty and he was able to stand upright and triumphantly exhibit a small black rock which looked in no way remarkable, but which, it was evident, he esteemed highly.
"Ah, my little gem," he said, gazing at it fondly. "You thought you'd escape me; but you didn't. A wonderfully fine specimen, boys."
"Tell yer what," said the yokel, from whom they had borrowed the spade, "I'll pay you fifty cents a day to clean up my back pasture yonder. It's chock full of them black rocks."