But now this mysterious sound became more pronounced, and forced a recognition.

The boys started, glanced at each other, and then each assumed a listening attitude.
There was a long silence, profound and unbroken; then a deep, sullen boom came floating down out of the distance.
"What is it!" exclaimed Joe, under his breath.
"I wonder," said Tom in a whisper.
"'Tain't thunder," said Huckleberry, in an awed tone, "becuz thunder--" "Hark!" said Tom.

"Listen--don't talk." They waited a time that seemed an age, and then the same muffled boom troubled the solemn hush.
"Let's go and see." They sprang to their feet and hurried to the shore toward the town.
They parted the bushes on the bank and peered out over the water.

The little steam ferryboat was about a mile below the village, drifting with the current.

Her broad deck seemed crowded with people.