"Haven't you got that stuff ready yet?" called the man with the drill. "I've got all the holes bored. Hurry up and get it in or it won't be hard by to-morrow, and there's no telling when that Hamilton kid may take a notion to drop in and visit his mine," and he laughed. "Oh, I guess I can keep him away for a few days yet," answered one, whom Dick recognized as Forty-niner Smith. "I've got a game I haven't played. But I guess this stuff is mixed enough. Say, it's the best scheme I've struck yet for 'sweating' a mine. Beats the shotguns all to pieces." From their hiding place the boys watched what the men did. The mixture with the gold particles in it was poured into the holes the man had dug. The boys could see now that it was not mortar, but concrete, which was being used. To Dick the whole scheme was now plain. The men poured a lot of gold dust into some concrete, and mixed it up with water until it was about as thick as paste. Then they put it into holes drilled in the rocky walls of the mine. The concrete hardened and became almost like the rock itself. Then, when a blast was set off, the rock, concrete and gold was all blown into small pieces, so that it looked as if the ore was of good, gold-bearing quality, whereas it was nothing but ordinary rock "salted." That was how the men were working to fool investors. They had taken an abandoned mine, from which all the gold had been dug, and, by this ingenious method, made it look, to the ignorant, as though it was a regular bonanza. "Well," remarked Dick, in a whisper, "we've discovered the trick. I guess dad's money and mine, too, is 'gone up the flume,' as the miners say. But I'm glad----" At that moment, Frank, who was balancing himself on a bit of rock, in order to see better, stumbled and fell, making quite a noise. The men turned as if a shot had been fired. "What's that?" asked Smith, in a hoarse whisper. "Some loose rock caving in," answered one of the men. "Come on, finish up. We've only got one more hole to fill, and by that time Nash will be ready to hoist us up." "That wasn't falling rock!" declared Smith. "Boys, I believe someone is spying on us. I'm going to take a look." Seizing one of the torches he started toward where Dick and his companions were hiding. "Come on!" exclaimed the millionaire's son, pulling Tim and Frank by the arm. "We've got to get out of this!" They turned and ran, their footsteps echoing on the rocky floor of the mine. They could hear Smith coming after them. His torch flashed around the turn in the gallery. He caught sight of them. "Stop!" he cried. "Stop or I'll shoot!" CHAPTER XXVI SIMON'S CONFESSION Dick gave a hurried look behind him. He could see something shining in Smith's hand--something that the light from the torch glinted on. "Keep on!" hoarsely whispered Tim. "He can't hit us down here. Keep on!"