Hawkins’ remark reminded every one in the laboratory, and particularly Merriwell, that Lenning was still to be found and dealt with. Merriwell’s faith in Lenning was growing. He had drawn certain inferences from the story told by his chums which strengthened his trust in his protégé.
“I think, Hawkins,” said Frank, “that it’s pretty clear now that Lenning wasn’t one of the robbers.”
“What makes it clear?” demanded the deputy sheriff.
Mr. Bradlaugh and Burke were opening the bag and examining the bars of bullion. Frank’s statement and Hawkins’ question claimed their attention, and they straightened up and looked around.
“Clancy and Ballard,” Merriwell replied, “recognized the voice of Shoup. The other fellow didn’t speak, so they were not able to recognize him by his voice. Now, Lenning and Shoup are enemies. It would have been impossible for them to work together.”
“Shucks!” grunted the deputy. “They only pretended to be enemies, sos’t Lenning could fool you into helping him get a job here.”
This was a most astounding theory. Furthermore, it was so wildly improbable that Merry and his chums had to laugh.
“You don’t understand what happened between Lenning and Shoup out at the camp in the gulch, Hawkins,” said Frank. “Shoup struck Lenning over the head with a paddle, knocked him out of a canoe, and came within one of drowning him. I guess they weren’t pretending they had a row—not to that extent.”
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Merriwell suddenly paused. He was talking in a loud voice—a voice that echoed in tremendous volume through the big room. He wondered what was the cause; and then, in a moment, he realized that the roar of the stamps had ceased. Twenty batteries, of five stamps each, had gone abruptly out of commission in the gold mill. The silence that hovered over the mining camp was most profound. Merry had been talking against the roar of the stamps, and when the roar ceased his voice was still lifted.
“What’s the matter with the mill?” he inquired.
“The stamps have been ‘hung up’ for an hour,” answered Burke, “so the amalgamators can dress down the plates.”
“It happens twice in every twenty-four hours,” put in Mr. Bradlaugh, “once on the night shift and once while the day men are on duty. We——”
Sim, who had started back to his work in the mill, returned and thrust his head in at the door just at that moment.
“Something queer goin’ on among the tanks, Burke,” he reported.
“Something queer, Sim?” echoed the super. “What do you mean by that?”
“Step outside once an’ use your ears.”
Not only Burke, but all the others, stepped from the laboratory building and stood at attention, facing the grim, black tanks. Thump, thump thump! came a hollow, reverberating note. There was nothing else, merely that thump, thump, thump! It came sometimes at regular intervals and sometimes a bit wildly and uncertainly.
“What is it?” inquired Mr. Bradlaugh.
“Blest if I can sabe it,” said Sim.
“How long has it been going on?”
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“Don’t know that, either. Mebby it’s been goin’ on for quite a spell, an’ that the roar of the stamps sort of smothered it. Now, when the stamps is all hung up, the thumpin’ can be heard plain.”
“It comes from the tanks,” put in Hawkins; “maybe it’s a leaky valve poundin’.”
“There’s nothing in the pipes,” said Burke. “The cyanide plant is out of commission until to-morrow. Sounds as though some one was striking a club against the side of a tank. We ought to be able to run it down and find out what causes it.”
Burke started off, mounting a plank incline that led to the lower row of tanks, and then moving slowly along a plank gangway that spanned the tanks’ tops. Merry, Clancy, and Ballard followed him.
It was difficult to decide just where the thumping sound came from. The hollow, resonant not............