"Give me my bone!"
Forrester puzzled over the words. They seemed merely absurd. What could their meaning be? It was a joy to know that Mackenzie or Jackson was above, and had discovered the place of imprisonment; but they must know little about it, after all, or they would be aware that it was impossible to send them an answer. Yet they must expect an answer; they would not have sent a message, mysterious as it was, unless they looked for at least an acknowledgment that it had been received. It occurred to him that the cleft might be used as a speaking tube: but a moment's consideration told him that it would be unwise to put this to the test. His voice might be heard by an enemy!
Beresford was so much exhausted after the day's work that Forrester did not mention the strange discovery to him that night. But the next day was an off day for him, and in the afternoon, after he was somewhat restored by rest and food, Forrester showed him the bone and the paper. The effect was electric. A look of eager hope dawned in the tired eyes. A murmur of thankfulness broke from his lips, and he lay for a while thinking.
"We have nothing we can write with," he said at length.
"Nothing at all. My pockets are empty," replied Forrester.
"Not even a pin?"
"No. Wait, though!" He felt along the edge of his waistcoat. "Yes, by Jove! I've one solitary pin. They would naturally overlook that."
"Prick the words through the paper."
"But what words?"
"Something that won't give anything away if the paper falls into the wrong hands. 'Give me my bone!' Answer, 'Take it!' Put the paper in the bone, fill up with dust, and replace it in the cleft when you get a chance. Leave the rest to our friends above."