"Is it tin?" asked Robert. "Well, I have known school-boys call it ’tin’ in the shape of sixpenny bits. It is silver. Now I’ll let you into my secret. The ore obtained from the farther gallery, and dumped down into that very convenient cavity, contains almost pure silver; there’s method in my madness, you see. Nobody knows it but yourselves; though I can’t say what some of the men may suspect. I don’t attempt to work it for the simple reason that I don’t want the news to get about. If it became generally known that I have struck silver, somebody might put in a claim to this neglected region, and I should either have to decamp or be in constant fear of attack. As it is, I think I am pretty secure; and when I have got a sufficient quantity of the ore I shall close down, dismiss the men, and carry the stuff to India." "But isn’t there silver also in the other gallery?" asked Bob. "No. The two metals, so far as I can discover, lie in parallel vertical streaks, with a band of quartz between them, and the men who are working at the copper know nothing of the silver a few feet away. You see now the reason why I keep the Kalmucks and the Pathans apart. The Kalmucks work the copper; they belong more or less to the neighbourhood; but the Pathans come from far distant parts, and if they should discover that their ore is silver, they are not at all so likely as the Kalmucks to bring unwelcome visitors upon me. I confess I was a little uneasy when I heard the explanation of that scrimmage we happened upon as we rode down. I wondered whether Nurla Bai’s presence in the Pathan section was due to some suspicion of the truth. But he has given no more trouble, and I hope that I was wrong." "He’s a sulky beggar," said Lawrence. "I can’t get a word out of him, and I don’t like those ugly eyes of his." "I’m watching him," said Mr. Appleton. "He works well, and has a great influence with the other Kalmucks. He’s certainly far and away more intelligent, and he has brought in a good many labourers. In fact, I had to put a stop to his recruiting. I wanted to keep the Kalmucks pretty equal in number to the Pathans, but, as you see, they already outnumber them by more than two to one. One great nuisance is their possession of firearms. I tried to induce them to hand them over when I engaged them, but in these regions the hillmen are as tenacious of their guns as our sailors are of their knives. Without my police Pathans and Kalmucks would be at each other’s throats." A few days after this conversation, the caravan which the boys had for some time been expecting arrived. It was larger than that which had accompanied them, and Mr. Appleton threw up his hands with a dismay that was not wholly feigned when he saw how many additional mules had been required for the transport of the aeroplane. "You said two or three," he remarked to Bob as the laden beasts defiled along the path; "but I’m sure there are seven or eight more than my stuff needed."