“What’s the matter?” asked Ralph.
“The water,” she said. “How high it is. It was much lower when I went to sleep, wasn’t it? I’m sure it was.”
“You’re right.”
“How do you explain it?”
“It’s a quite natural phenomenon, like those bells,” he said quickly. Then in reassuring accents, he added: “The lake is subject to the law of the tides, which, as you know, produces an ebb and flow.”
“But when is it going to stop rising?”
“In an hour or two.”
“That’s to say that the water will fill half the grotto?”
“Yes. It certainly does flow into the grotto, as this black line on the wall, which is evidently the high-water mark, proves.”
He had lowered his voice a little. Above the black line to which he had pointed, there was another just under the ceiling of the grotto. What did that one mean? Was he to understand that at certain periods the water would reach the ceiling? But owing to what exceptional phenomena, to what immense cataclysm? [[272]]