They went on. Lawrence shot a ptarmigan which would give colour to the ostensible object of their walk. Then they turned and retraced their steps. As they pa.s.sed the b.u.t.tress Bob looked carefully for the rope, and could just discern it by its slight motion against the background of rock.

"You might pa.s.s a dozen times and never notice it," he said.

Facing in the same direction as the current they were now able to take a more comprehensive view of the gorge.

"Where would you make your plunge if you wanted to swim across?" asked Bob.

Lawrence looked along the bank.

"There!" he said after a little, indicating a rock a few feet below and beyond them, that jutted out into the river.

"Well, let's go and take a look from there."

They left the track, climbed on to the rock, and sat down there with their knees up, flinging pebbles aimlessly into the water.

"I think you're right," said Bob. "Allowing for the strength of the current it's just about here that I should take the plunge. The oblique distance between this and the rope would make the diagonal--parallelogram of forces, you know."

"I don't suppose Nurla knows anything about that," said Lawrence with a smile. "But look here: don't these bushes look as if they'd been disturbed recently?"

He nodded his head towards some scrubby bushes at their right hand.

"You'd think so, certainly," said Bob. "Still, we may be wrong. I remember old Colonel Fanshawe warning us against the danger of seeing what we wanted to see."

After sitting a few minutes longer, keeping up the appearance of aimlessness by careless tossing of pebbles into the water, they rose and resumed their walk. But just at this moment Lawrence caught sight of a dark object among the bushes that grew spa.r.s.ely on the hillside above the track, twenty yards away. At the distance, partially concealed by the foliage, the nature of the object was not apparent; but Lawrence clambered up by means of the bushes, and discovered a long coil of thin strong cord, lying between two inflated water-skins. He left them where they were, and returned to the track.

"It's clear as daylight," said Bob, when he had heard his report. "The fellow fastened the cord to the rock and held on to it when he took the water. He supported himself on the skins, and when he got to the other side, attached cord and skins to the dangling rope. When he came back, he hauled himself hand over hand against the stream, and pulled in the cord after him. That cord will, metaphorically speaking, hang the fellow, but he's clever enough to have deserved a better fate."

They returned slowly to the compound, well pleased with the result of their investigations.

A few minutes after they had gone, a small figure rose from among the bushes within a few yards of the spot where the cord was placed.

Clambering up the hillside, and screening himself as much as possible behind clumps of vegetation, and by the natural inequalities of the ground, the little man made his way rapidly in the same direction as the Englishmen, and descended unseen among the huts of the Kalmuck miners.

His narrow little eyes were gleaming with excitement. The men were just returning to work. The Pathans had already crossed the drawbridge; the Kalmucks were crossing. Black Jack pushed his way into the throng, apparently in a great hurry. He overtook Nurla Bai at the entrance to the mine gallery, and together they disappeared.

The boys lost no time in communicating their discoveries to Mr.

Appleton.

"This is getting warm," he said. "We can do nothing yet. Act as though nothing had happened: to-night we'll talk things over. You're sure none of the men suspect you?"

"There's no sign of it," said Lawrence. "They saw us go, and come back with a bird: a very ordinary thing, that. I flatter myself that a Scotland Yard detective wouldn't have guessed from our manner that there was any other object in our walk."

The day pa.s.sed like every other day. At sundown the bugle's note drew the men from their work. They returned to their several quarters, and after their evening meal settled down to their games of chance or skill.

After supper, when pipes were lit, Mr. Appleton returned to the subject.

"I haven't a doubt that Nurla is the man," he said. "You remember his industry when you were building your bridges. The scoundrel's motive is clear. The question is, what is he after? It can't be mere inquisitiveness. He suspects that the Pathans are mining something more valuable than copper, and if he can prove it, he'll sell his knowledge, I suspect, and we shall have trouble. I only hope that your appearance last night disturbed him before he had had time to get any samples."

"If it didn't?" said Bob.

"He'll probably try again. The fact that he hasn't absconded seems to show that he isn't satisfied. If he had got enough for his purpose he would have been over the hills before this. We must keep a strict watch, and if we catch him making any further attempt of the same kind it's the sack at once."

"Wouldn't it be best to sack him now?" Lawrence suggested.

"I'm rather loth to act without definite proof. We should make an enemy of the fellow needlessly, and he has such influence with the Kalmucks that he might call them all out."

"Would that matter? The silver's the thing," said Lawrence.

"Not at all. If I went on mining without them it would be a clear proof that I could afford to leave their gallery unworked, and there'd be trouble all the same. There'll probably be trouble anyhow, but I'd rather keep the Kalmucks working quietly as long as possible. Meantime we'll take precautions. I'll put a Sikh in the Pathan section to keep guard through the night, and withdraw him before dawn, so that n.o.body is any the wiser."

Early next morning, a few minutes after the bugle had sounded reveille, the Englishmen were disturbed in their dressing by the sound of a great uproar from across the river. They flung on their coats and hurried out. The drawbridge had not been lowered; half an hour would elapse before the bugle called the men to work. But at the farther end the Pathan miners had a.s.sembled, and were gesticulating in much excitement, shouting l.u.s.tily for the huzur. Mr. Appleton ordered the drawbridge to be let down, and hastened across to meet the men.

For some time he found it impossible to gather anything definite from their frenzied clamour. Then, singling out one man as a spokesman, and bidding the rest be silent, he heard a startling story. Muhammad Din, the Pathan foreman, had been discovered in his hut with a knife in his throat. Mr. Appleton had a great liking for the man--a rough uncouth fellow, but an excellent workman and very popular with the men of his race. He at once gave orders that Muhammad should be carried across the bridge to the house, and announced that he would hold an inquiry after breakfast.

In knocking about the world he had picked up a knowledge of rough and ready surgery and medicine, and had more than once treated sick men. A short examination showed that the wound in the unconscious Pathan's throat was serious, though not necessarily mortal, and he set to work at once to cleanse it with antiseptic lotion and to bind it up. While he was still in the midst of this task, more surprising news was brought from the other side.

Quarrels between the Pathans and the Kalmucks had been so frequent in the early days of the settlement that Mr. Appleton had had to devise a plan for minimizing the risk of such outbreaks. The quarters of the two parties were separated by a neutral zone nearly a hundred yards in breadth, which they were strictly forbidden to cross. They used it in common only when going to and from their work, and then at different times, the Pathans leaving first and returning last. If a Pathan wished to go down the river, he had to climb the hillside and come down to the track beyond the Kalmuck camp. If a Kalmuck wished to go up the river, he had to make a similar circuit. The stables were placed in the neutral zone.

When the attack on Muhammad was discovered, and the Pathans rushed to the drawbridge, the Kalmucks were aroused by the din, and flocked to the fence marking the boundary line. But they were unaware of what had happened until their turn came to cross the bridge and they heard the story from the Sikh on duty. A few minutes afterwards, however, it was discovered that neither Nurla Bai nor his dwarf henchman was among their party. No sooner was this reported than the head stableman rushed excitedly across the bridge, to announce that the ponies on which the two boys had ridden to the mine had disappeared. These successive discoveries threw the whole community into a state of seething agitation. Instead of going to their work, the men gathered in groups, discussing the strange thing that had happened to their foreman.

Already the Pathans were shouting accusations of Nurla Bai across their fence, and Gur Buksh with his armed squad stood ready to intervene if the wild pa.s.sions of the miners led from recrimination to blows.

Mr. Appleton did not allow these events to interrupt his ministrations to the injured Pathan. When Muhammad, with his wound well dressed, had recovered consciousness, and was laid in one of the outhouses belonging to the domestic staff, Mr. Appleton and the boys returned to their rooms to finish dressing and breakfast.

"It's all as plain as a pikestaff now," said the elder man. "Nurla has got all he wanted; he must have guessed that he was suspected, and very wisely decamped. And he paid off his old grudge against Muhammad before he left. He's got your ponies too. That's what they call robbery with violence, I think."

"What shall you do, Uncle?" asked Lawrence.

"Go after him, of course. I couldn't otherwise hold the Pathans for an hour. They know I'm just, and as good as my word. If I tell them that Nurla shall be caught and punished they'll believe me and remain as quiet as Gur Buksh can keep them. Otherwise they'd desert in a body and hunt the hills themselves."

"Nurla's got a good start: it won't be easy to catch him," said Lawrence.

"You forget Bob's aeroplane, my boy," said Mr. Appleton.

CHAPTER THE SEVENTH

NURLA AT BAY

If Mr. Appleton had wished to atone for the coldness of his former att.i.tude to airmanship, he could scarcely have shown more eagerness to make use of the aeroplane in hunting down the fugitive malefactor. He was blind to the difficulties. To guard against a disappointment, Bob ventured to point out the disadvantages under which the pursuit would be conducted--the few landing-places and fewer starting-places which the rugged country offered; the ease with which the men, even if discovered, might conceal themselves in some woody ravine or some inaccessible cleft in the mountain side: the likelihood of their escaping notice altogether. There was every chance indeed that they would be espied, if at all, upon some tract of country where to make a descent would be impossible; and before the pursuers could reach a suitable spot, there would be plenty of time for the men to alter their direction and elude the most careful search. The one point in favour of the pursuit was that Nurla was accompanied by Black Jack: it would not be so easy for two as for one to escape notice.

Mr. Appleton ignored all Bob's well-meant hints of failure, and was only anxious to be off. He summoned the Pathans and explained to them what he was about to do, warning them against misbehaviour in his absence. He gave instructions to Gur Buksh to maintain strict discipline, and flattered the Kalmucks into good temper by a.s.suring them of his belief in their loyalty. Then, having arranged that a small party of Pathans should ride northwards down the track, he hurried after the boys, who had already gone to prepare the aeroplane for flight.

He had no doubt that Nurla had fled northward, in the direction of his own people. For at least forty miles the fugitives would be obliged to keep pretty closely to the valley, for, as far as Mr. Appleton and any of his people knew, there was no practicable way over the hills for horses. After that the country began to open out: the river broadened and was fordable in several places, and the fugitives would have the choice of several routes, either to the right or the left. It was therefore necessary to overtake them and hold them up while they were still in this forty-mile stretch of rugged river valley. Mr. Appleton's idea was to fly ahead of them as soon as they had been sighted, land at the first convenient spot, and hold them in check until the mounted party had had time to come up. It was impossible to tell how many hours'

start the men had had; but even if they had left the settlement soon after dark their progress along the rough and dangerous track must have been slow, and it seemed hardly likely that they could reach the open country before the swift-flying aeroplane overtook them.

The boys rapidly overhauled the engine and tested the steering and controlling gear. Bob felt a trifle anxious when he noticed how rapidly the clouds were racing before the wind, which blew from the west.

Flying in the valley, the aeroplane would be protected from the full lateral force of the wind by the high mountain barrier on each side.