"How far apart?"

"Width of two fingers, sahib."

"And how large is the hole?"

"As long as my outstretched arms, and a little wider than my spread fingers."

"Big enough to crawl through?"

"If you were flat as a flounder, sahib."

"Can you see to the bottom of the hole?"

"No, sahib: it is dark, and goes deep."

"Next time you come, bring me a small marrowbone, not wider than your two fingers. Fill it with dried marrow, closely pressed together. Can you get any paper?"

"There is rice paper in kitchen, sahib."

"Bring me a piece, and something I can write with--a blackened stick, or a bit of charcoal. You will remember?"

"Like a book, sahib."

Fingering his beard meditatively, he walked away.

"What do you mean to do?" Jackson asked, when Mackenzie had repeated what Hamid had told him, and the instructions he had given.

"Put a wee note inside the bone, and get Hamid to fling it down the grating."

"But if it falls into the wrong hands, and is taken to the Old Man? He speaks English: he may read it too."

"What I write will only puzzle him."

"In any case, what's the good? Suppose d.i.c.k is there. How can he send an answer?"

"I've my notion about that, Bob. All depends on Hamid; but, as I said, he is no fool; he will do what we tell him, and take every care. I wish it were to-morrow!"

"What puzzles me is the Eye. What on earth can it be?"

"That beats me. Clearly it is harmless at times; Hamid didn't notice it. I think it's a kind of box, containing some destructive substance in a concentrated form. The Old Man evidently has some device for opening it without harm to himself. One thing is very clear."

"What's that?"

"Och, man, that the old wretch must be very human after all, or he couldn't have the stomach ache."

CHAPTER XV

THE MOLES

"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."

"p.r.i.c.k 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."

The guard kept by the priest and the negritos was little more than a form. The abject condition of the Chinese prisoners precluded any likelihood of revolt. Consequently no real watch was kept at night, and the only risk was that an unusual sound might awaken one of the three somnolent figures at the entrance. Forrester was careful to move very quietly when he returned to the cleft that night, though after all there was little chance of a slight sound from the inner cavern reaching the priest's ears.

On reaching the cleft he looked in eagerly for the string which he half expected to find there. He was not disappointed. A few feet from the opening, but within easy reach, lay another bone, with a string attached. He replaced this by the bone containing the paper, and stole back to his friend. The second bone held no message.

"We shall hear from them again to-morrow," said Beresford hopefully.

Next night, when Forrester visited the cleft, he found the bone on the end of the string, untied it, and hurried back with it to Beresford.

Shaking out its contents, he found a somewhat larger screw of paper, enwrapping a sharpened stick of charcoal. On it, when opened out, he read: "String 65': hole 3' x 10": grated: where are you? Reply at once.

M."

"He evidently thinks communication safe at night," said Beresford. "We can't tell him everything. Just write: 'Cavern. Boring chimney through roof. More to-morrow.'"

Forrester wrote the message, adding 'B. is here,' replaced the paper, and returning to the cleft, tied the bone again to the string. It occurred to him to give a slight tug. The string gave slightly, then stretched taut. It was evidently fastened to something above.

It was long before the Englishmen fell asleep that night. They discussed in whispers the information they had gained, and their future course of action. They could not but conclude that the cleft, narrow as it was, was the avenue by which the negrito had escaped; but what was possible to his diminutive frame was impossible to them. The grating had probably been placed over the hole after his escape was discovered, to prevent a second attempt. It was clear that the cleft was not perpendicular, or the little man could hardly have climbed up it. If they could ascertain the angle of its slope, they might calculate the vertical distance, and learn how long their chimney through the roof of the inner cavern must be made. They had no means of discovering this fact, which would have been so useful to them; but it seemed probable that, allowing for the steepest practicable slope, the chimney must be pierced for at least forty feet before it reached the surface.

By gradually lengthening the bamboo pole, and clearing the dust from the sides of the chimney, they had already extended the range of the rays nearly twenty feet above the roof, and more than thirty feet above the floor of the cavern. They had now no more bamboo rods; the pole could not be lengthened further; it was impossible to remove the dust at a greater height without a ladder to stand on. But, with communications open, a ladder might no longer be an impossibility. With a knife and some stout string they might form one of bamboo, and still leave enough for a pole wherewith to continue their work of removing the dust.

Forrester resolved to ask for these articles at the first opportunity.

Beresford pointed out the importance of letting Mackenzie know the spot at which the chimney, when completed, would reach the upper air. It might prove to be in the very quarters of the enemy. In that case the chances of escape would seem to be remote indeed. But Mackenzie was cautious as well as shrewd, and with this necessary information in his possession he would know how to direct his own course, and what advice to give his friends below.

Accordingly, next day Forrester carefully paced the distance between the cleft and the pit in the inner cavern. Allowing as accurately as he could for the windings of the pa.s.sage, he gauged the length to be approximately fifty yards in a straight line. At night, he found on opening the paper secreted in the bone that Mackenzie had antic.i.p.ated him. "Cleft--?--> chimney." he read. He crossed out the query and wrote "50 yds.: cleft on right," adding: "Send knife + stout string."

He returned to the cleft several times during the night in the hope of finding the things asked for; but it was not until the next night that they came: a large kitchen knife such as is used in boning meat, and about a dozen yards of thin hempen cord.