“Cisterns!” said Gorman. “What the devil did you put cisterns into a cave for?”
“We didn’t put them. They were there. Galvanized iron cisterns. Huge things. Oh, I promised I wouldn’t tell any one about those cisterns. They’re part of the secret of the island. The Queen made me promise. I wish I hadn’t told you.”
“You’ve broken your promise now,” said Gorman. “You may just as well go on.”
It took some time to persuade Phillips to go on; and all Gorman’s sophistries would not induce the boy to say another word about the cisterns in the cave. They were the Queen’s part of the mystery of the island and he would not speak of them. But he did at last confide in Gorman to some extent.
“I think,” he said, “I may tell you about this. I found this out myself.”
He took a letter-case from his pocket and produced from it a corner torn off an envelope.
“Look at that,” he said. “Look at it carefully.”
Gorman stared at the scrap of paper.
“Bit of an envelope,” he said. “Penny stamp, London postmark.”
“Now look at this,” said Phillips.