Hastily donning robes and slippers, the girls gathered about Cora as she
rang the electric bell which had been arranged to summon the boys in the
other bungalow to the toy telephone. Meanwhile, Mrs. Floyd had arisen
and dressed to let in the boys. The rumbling, trembling noise had
stopped.
"Oh, why don't they answer?" cried Cora, impatiently pushing the
electric bell button again and again.
Then, through the toy receiver came a faint voice.
"Hello! Hello, there! Is that you, girls? What is the matter?"
"This you, Jack?" Cora asked.
"Yes."
"Come over as fast as you can! Hurry!"
"What's the matter?" he asked.
"Don't stop to question! Hurry over!" Cora begged. "It's that terrible
noise again. Can't you hear it?"
"No," answered Jack. "But we'll be right over. Come on, fellows!" Cora
heard him call to Walter and Paul, as he left the telephone. "The girls
are scared."
"I guess he'd be too, if he heard that noise," Cora said. "Did you all
hear it?" and she appealed to her chums.
"I did," affirmed Hazel. "It sounded like distant thunder."
"Could it have been?" asked Mrs. Floyd, who had joined the girls.
"The stars are shining," reported Belle, looking from a window, shading
her eyes with her hands from the light in the room. They had partly
dressed and gone down to the living room. There they listened and waited
both for a recurrence of the noise and for the approach of the boys.
The latter made their presence known first, fairly running along the
graveled way that led from their bungalow, over the rustic bridge, to
the girls' abiding place.
"What's all the racket about?" demanded Jack, as he and his two chums
entered, rather breathless from their run and their hurry in dressing,
the hurry showing itself in the absence of collars and ties.
"It's that noise," said Cora, her voice trembling slightly. "We heard it
again, Jack."
"Was it so scary?" demanded Paul, looking at his sister.
"It certainly was--too scary for words!" answered Belle. "I'm not going
to pass another night in Camp Surprise!"
"It _has_ been a surprise with a vengeance," declared Bess. "Boys, can't
you do something?" she appealed.
"What's to be done?" asked Jack. "We'll have to wait until we hear the
noise again, and then we can tell from which direction it comes.
Suppose, while we're waiting, you girls just tell us what you heard."
They had all heard something different, it developed. At least, they all
had a different impression of the noise.
Cora described it as a "trembling roar."
Bess said it was a rumble, as though a heavy wagon had passed in front
of the bungalow.
Belle said it reminded her of a deep, heavy sound, such as she had once
heard in a blast furnace.
It was reserved for Hazel to describe accurately the noise, though none
of them knew her description was correct until afterward.
"It was like a factory or machine shop next door," said Paul's sister.
"It seemed to shake the bungalow as though heavy machinery were
working."
"It must be the waterfall," decided Jack. "Only a large body of water,
tumbling down into some chasm, could make a noise like that. There's no
machinery around here. Besides, the waterfall is bigger than ever now,
on account of the rain. It must be that."
"It wasn't!" declared Cora, though when pressed for reasons to bolster
up her denial she could give none. "It wasn't that sort of noise at
all," she affirmed. "It was more like----"
"What's that?" asked Belle so suddenly that the other girls jumped
nervously.
It was the sound of a footstep on the porch, a firm, unhesitating
footstep.
"I expect that's my husband," said Mrs. Floyd.
It was Mr. Floyd, and he was, greatly surprised to see the "whole family
up," as he expressed it.
"What's the matter?" he asked, looking around on the circle of rather
startled faces, ending with his wife's. "Did you sit up to see how late
I got in? Strictly business, young ladies and gentlemen," he went on,
smiling at them. "The committee had considerable to transact, and I had
to stay."
"This is a sort of surprise party," Cora told him. "Camp Surprise is
living up to its name," and she went on to tell about the noise, the
others adding bits here and there.
"Pshaw now! That's queer!" commented Mr. Floyd. "I have heard them
rumblings myself, but I laid 'em to the waterfall. It's a curious
cataract at times."
"This noise," began Cora, "isn't like anything I ever----"
She paused midway in the sentence, and a strange look grew and spread
over her face, as it did over the faces of the others.
"There it is now," whispered Bess. "That--that noise!"
They all heard it, a dull, rumbling roar that made the bungalow tremble
as when a heavy wind blows and vibrates the timbers of a house.
"So that's what it is!" exclaimed Jack. "This is my first experience."
"I heard it once, though distantly," said Walter.
"Listen!" cautioned Cora.
The noise seemed to increase.
"Say, that is curious!" commented Mr. Floyd. "I never noticed that
before. Where does it come from?"
Hardly had he spoken than the rumbling ceased, and there came a sharp
crash, as though wood had broken somewhere.
"The chimney's fallen!" cried Mrs. Floyd.
"Nonsense, Eliza," said her husband. "The crash would be up on the roof
if the chimney toppled over. Besides, there's no wind, and the noise
didn't come from above, it came from--down there!"
He pointed to the floor of the living room, which was of bare boards,
with rugs here and there.
"That's right!" cried Jack. "The crash was below us. It's under this
bungalow somewhere. Up with the floor boards! We'll get at the bottom of
this!"
There was no doubt on that score. Every one in the room was sure the
noise had come from under the floor.
"But how could it?" asked Walter. "There's no cellar to the bungalow; is
there?"
"None that I ever heard of," said Mr. Floyd. "I didn't live here when
the bungalow was built, but I've always understood it had no cellar."
"It hasn't," Cora affirmed. "At least none that you can find. There are
no cellar stairs and the place seems to rest on piles."
"But the noise came from down there," and Jack pointed to the floor.
"The only way to find out is to take up the boards. May we, Mr. Floyd?"
"Why, yes, I reckon so. We've got to get at the bottom of this. It's
better to spoil the floor than to lose the renting of the bungalow by
ghosts scaring tenants away. Take up the boards. I'll get an axe and a
crowbar."
And so, in the middle of the night, for it was close to twelve o'clock,
the strange work of looking under the floor of the bungalow for the
source of the queer noise was begun.
"Where shall we start?" asked Jack, when Mr. Floyd had brought the
implements.
The caretaker considered a moment.
"If there is some sort of cellar, or space under this bungalow, it must
be near the center of the floor, I'm thinking. We'll begin there. Don't
be afraid of spoiling the floor. I'll take the responsibility."
Jack swung the axe vigorously, and, being aided by Walter, soon had
removed two or three of the narrow boards. As they were prying on
another, a queer thing happened.
A solid section of the floor from the middle of the room suddenly sank
down, and then rolled back, exactly as a sliding door rolls, only this
door was horizontal instead of vertical. Back it rolled, leaving what
was practically a trap in the floor, and as the light shone down this a
flight of steps was revealed leading into darkness.
"Great bumblebees!" gasped Jack. "See what we've done! Uncovered a
secret passage! Now for the solution of the mystery!"