In the walls there were rusty iron staples, intended as footholds, and so used by the men. He descended, examining the walls and the staples; there was nothing strange about them. "The brickwork is just about six feet below the surface," he thought. "I'll measure the same distance here." At a little more than his own height below the ground he scrutinised the masonry carefully. There were slight clefts where the separate stones met, but nothing unusual in their appearance. He pushed and strained at the stonework, without effect. Then he noticed, just within arm's reach to his right, a staple quite out of line with the rest. It seemed to have been fixed in the wall without purpose. Leaning over, he pulled at it, at first cautiously, then more and more vigorously. [Illustration: GAMBARU IS AMAZED] Suddenly he felt a shock of surprise. Was the staple moving, or was he himself? He planted his foot firmly on the staple on which he was standing, and still pulled. There was no doubt about it; he was slowly swinging round. The huge slab of stone against which he was supporting himself had moved inwards on his right, outwards on his left, and he was turning with it. Now thoroughly excited, he tugged steadily, and in a few moments found himself looking into a dark aperture in the wall. "Eureka!" he exclaimed joyfully, and Gambaru, leaning over the brink of the well above, gasped with terrified amazement as he saw his master disappearing. "A candle!" shouted Royce. The Hausa sprinted away, and returned with the whole garrison at his heels. "Back to your places, you idiots!" cried Royce. "Kulana, keep them at their posts. Give me the candle, Gambaru." Holding the lighted candle, he stepped from the staple into a low dark passage, and groped his way stoopingly along it. For some forty or fifty yards it was narrow; then all at once it opened into a huge natural cavern, warm and stuffy, with an earthy smell. Royce looked about him and gasped with astonishment. The candlelight fell on an enormous store of elephants' tusks, huge and massive objects ranged in close-packed rows, and filling nearly three parts of the cavern. "My word! What a find!" Royce exclaimed. He began to count the tusks, came to a hundred, and gave it up. "Five hundred, at a guess," he thought. "They must be worth a fortune. No wonder Mr. Goruba wanted to strangle me! ... What's that yonder?" He went farther into the cavern. Beyond the tusks lay an assortment of many things--ivory cups, vessels of gold, an old French musket, swords, scimitars, a kepi or two, a French officer's sash, some cartridge cases, several native spades and pickaxes--and, at the far end, objects which caused him to recoil. They were human skeletons.