ce. He's
always out collecting."

"Does he always carry a quarry like that around on his back?" asked
Tom.

"Always when he's getting specimens," Dick whispered back.

By this time the professor, his eyes agleam over his latest discovery,
was back at the side of the car.

"Ah, my beauty, I have you safe now," he said, patting the side of the
bagful of specimens. "Boys, this is my lucky day."

The boys could hardly keep from smiling at the little man's delight.
It appeared hard to believe that anyone could find pleasure in packing
about a sackful of heavy rocks on a hot day. But the professor's eyes
were sparkling. It was clear he considered himself one of the most
fortunate of men.

Dick introduced the boys and, to their surprise, the professor
declared that he had read of their various adventures and inventions.

"We are actually fellow adventurers in the field of science," he
cried, rattling his bag of specimens enthusiastically. "Some time I
should like to call on you and see your workshops."

"You will be welcome at any time," said Jack cordially, and then the
professor declared that he must be getting home.

"If we are going your way we can give you a ride," said Tom.

"Thank you, I'll accept that invitation. But what an odd-looking
automobile you have there."

The boys explained to him that it was a new type of car that they were
trying out for the first time and then Dick helped the scientist lift
his bicycle into the tonneau. He would have helped him with his
weighty load of specimens, but the professor refused to be parted from
them. As they started off again he sat with the bag firmly gripped
between his knees, as if afraid someone would separate him from it.

The professor lived with a spinster sister to whom his specimens were
the bane of her life. As the car rolled swiftly along, he occupied his
time by peeping into the bag at frequent intervals to see that none of
the specimens, by some freak of nature, flew out.

All at once he reached forward and clutched Jack by the shoulder.

"Stop! My dear young friend, please stop at once!"

"What's the matter?" asked Jack, slowing down at the urgent summons.

"Look! Look there at that rock!"

To Jack the rock in question was just an ordinary bit of stone in a
wall fencing in a pasture in which some cattle were grazing. But
evidently the professor thought otherwise.

"It's a fine specimen of green granite," he exclaimed. "I must have
it. How di