The next day, the boys were outdoors from morning until night, skimming over the surface of the bay in their ice-boats, skating on an improvised rink down by the shore, and enjoying themselves on the ski slide. Frank, for the time being, seemed to have dismissed the mystery of the notebook from his mind. That evening, as the boys sat in front of the fireplace, the Sparewell case was not even mentioned. It was a windy, stormy night and the cabin creaked in the gale.
“Must be a good, strong chimney to hold up in a wind like that,” remarked Chet.
“Why shouldn’t it?” said Biff. “It’s made of solid stone.”
“I know; but the wind gets a terrific sweep when it hits this island. That chimney isn’t so new, either.”
“Stone chimneys will last a hundred years,” scoffed Joe.
Chet pointed to the big fireplace.
“This one won’t. Look. You can see where it is cracked already.”
The boys inspected the chimney. They saw that Chet had noticed something that none of them had observed before. There was a distinct crack across the surface of the stone near the ceiling.
“It doesn’t look any too secure at that,” remarked Frank. “A crack like that might easily cause a fire.”
“It sure could!” exclaimed Biff.