sliding headlong. The forest thinned. They emerged beside a long ridge of rock, partly covered with moss and shrubs, that stuck out of the ground like the back of a giant beast.
“It’s not far from here,” said Danny, with satisfaction.
Joe groaned. “Not far! That’s what you’ve been saying ever since you talked us into coming with you this morning. If you had told me I was going to have to climb up over Sugarloaf—!”
“Yes, Dan,” said Irene. “Why couldn’t we have come right up this side, nearest the town? It would have been shorter.”
Danny nodded. “I know. But the trouble is, when I first found the cave, last spring, I didn’t mark the trail to it. I was looking for mineral specimens for my collection and I took the road from the end of town up behind Sugarloaf, and past Rose Hill. Then I climbed Sugarloaf and started down this side. So I remember the landmarks from this direction but not the other.”
He made his way down the slope until he was standing in the shadow of the ridge. When his friends had joined him, he said, “Now, let’s see. I followed the bottom of the ridge and came out on a kind of point of ground where there was a big white oak. The cave was just below it…I think.”
“You think?” Joe said.
“No, I’m sure of it. Stop worrying, Joe.” He strode resolutely on. But suddenly, Irene caught his sleeve.
“Listen,” she said. “What was that?”
They stood still, cocking their heads. “I don’t hear anything,” said Danny.
“There it is again. Shh!”
They all heard it now, a faint, sharp tapping as of metal striking stone. It seemed to come from the ridge at their backs.
“That’s just a woodpecker,” Danny said, shrugging.
“Doesn’t sound like a woodpecker to me,” said Joe. “More like a pebble-pecker. Tell you what—let’s go home.”
Danny frowned at his friend. “You don’t really mean that, Joe.”
“I don’t? Oh. I thought I did.”
“And anyway, I’m not going to turn back now,” Dan went on. “When I found the cave, I didn’t have any light with me, not even a match. I planned to come back next day, but the next day was a school day and I forgot. Then, next time I remembered about it there was a baseball game I had to play in. Something always interfered—that camping trip one week end, and then Irene’s birthday, and—gosh, all sorts of things. I wouldn’t have thought of it today, except that Professor Bullfinch said something about his old friend, the geologist, coming to visit us. Now that we’re here, nothing’s going to stop me.”
Joe sighed. “Oh, I know. But trouble can come to you out of a clear blue sky, Danny. Like that time you promised Miss Arnold you’d never meddle with the science experiments in class again. Then, you dropped a little sulphur in that test tube when she wasn’t looking. Phew! It took days to get the smell out of the classroom.”
“I just wanted to see what would happen,” Danny said, indignantly. “But anyway, that’s got nothing to do with today. This time, we’ve got flashlights, there won’t be any trouble, and nothing’s going to happen.”
He turned away. Before he could take another step, something rang against the stones above his head, shot out into the air, and landed with a thump in the grass at his feet as if it had dropped from the sky.
CHAPTER TWO
Danny’s Choice
For a long moment, the young people stood motionless, staring. Then Danny stooped to pick up the thing.
“Don’t touch it!” Irene gasped.
“Why not?” said Danny. “It’s only an old hammer, after all.”
He turned it over, examining it curiously. Joe tilted his head back. “What’d I tell you?” he said. “I didn’t hear any plane. That thing must have fallen from a flying saucer. Are you sure it’s just a hammer? Maybe it’s a death ray shaped like a hammer.”
“I’m almost sure it isn’t,” said a strange voice. Looking upward in astonishment, the three saw a short, weather-beaten man regarding them from the top of the ridge. He was dressed in a corduroy jacket patched with leather on the elbows, but there was nothing ragged or dirty about him. He had the look of one who had traveled far, an outdoorsman, or an explorer. His hair was white above his sunburned face, but his eyes were bright blue, sharp, and lively.
“I’m terribly sorry,” he said. “I hope nobody was hurt.”
“We’re all right,” Danny answered.
The stranger climbed quickly down the ridge. “I had just chipped out a fine little cephalopod, and I laid my hammer on the rock above me. It slid down.”
He held out a lump of stone and the young people could see that it had a faint marking on it, or rather, in it: a small, coiled shape like a snail-shell.
“That’s what I found,” said the man.
“That’s a sifflepod?” said Joe. “It looks like a snail.”
“The cephalopods were mollusks, something like—well—sea snails,” the other said.
“Oh, then you’re a fossil hunter?” asked Irene.
“Not exactly. I’m a geologist. But I can’t resist a nice specimen.”
“I knew you were a geologist,” said Danny. “I could tell by the shape of your hammer. Are you working at Midston College?”
“Oh, dear no,” said the other, with a smile. “I’m just visiting here. Although heaven knows what Bullfinch must think. I knew I ought to phone him, but when I got off that early train and looked up at these hills, I thought to myself, ‘What beautiful examples of sedimentary rock!’ I got out my hammer, left my suitcase in the waiting room, and—well, here I am.”
At the mention of Professor Bullfinch’s name, Danny snapped his fingers. “Now I know who you are,” he exclaimed. “You’re Doctor Tresselt, and you’re coming to stay with us.”
“I am undoubtedly Dr. Tresselt,” said the geologist. “But I think you’re mistaken. I’m going to stay with Professor Bullfinch. Not that I wouldn’t like to stay with you,” he added, in a kindly tone. “I’m very fond of children. I have three or four of my own.”
“I know,” Danny said.
“You do? I didn’t think my children had any friends in this neighborhood.”
“No, I mean I know you’re going to stay with Professor Bullfinch. I live with him. I’m Danny Dunn. My mother is his housekeeper.”
“Well, I’m delighted to meet you,” said Dr. Tresselt, shaking the boy’s hand warmly. “And these are your brother and sister, no doubt?”
Irene giggled. “My name’s Irene Miller, Dr. Tresselt. I live next door to Dan.”
