Arthur rushed indoors. When Estelle followed him she found him excitedly examining the marble floor about the base of the vault.
"It's cracked," he said excitedly. "It's cracked! The vault rose all of an inch!"
Estelle looked and saw the cracks.
"What does that mean?"
"It means we're going to get back where we belong," Arthur cried jubilantly. "It means I'm on the track of the whole trouble. It means everything's going to be all right."
He prowled about the vault exultantly, noting exactly how the cracks in the flooring ran and seeing in each a corroboration of his theory.
"I'll have to make some inspections in the cellar," he went on happily, "but I'm nearly sure I'm on the right track and can figure out a corrective."
"How soon can we hope to start back?" asked Estelle eagerly.
Arthur hesitated, then a great deal of the excitement ebbed from his face, leaving it rather worried and stern.
"It may be a month, or two months, or a year," he answered gravely. "I don't know. If the first thing I try will work, it won't be long. If we have to experiment, I daren't guess how long we may be. But"—his chin set firmly—"we're going to get back."