“Well, you got back all right, did you?” said Goldrick, as they came up. “How are things looking down along?”

They told him of the O. C. trestle-building, and of the slope-side gang they had seen just below the Pine Gulch camp. While they were talking a distant thunder-burst of heavy blasts jarred upon the air.

“That must be that gang we saw a few minutes ago,” said Dick, adding: “It’s sort of curious. They weren’t drilling when we came by, and we didn’t see any air compressor or machinery of any kind.”

“All right; let ’em waste their dynamite if they want to,” said the young engineer. “We’re going to beat ’em, hands down.” Then to the matter in hand: “If you two cubs want to do a bit of surveying, you may take an instrument and run a trial level for Bannagher in that rock cutting. He’s lost his bench marks in the shooting.”

Delighted to get a chance at real instrument work, the two boys hurried back to camp, got a transit, and were presently hard at it, running lines for the hard-rock foreman. Absolute accuracy wasn’t necessary, of course; if it had been, Goldrick would have run the lines himself. Just the same, the two understudies, working with the instrument, were as painstaking as they knew how to be, and that was why Dick, taking his turn at the eye-piece of the telescope, burst out suddenly:

“Say, Larry—gee whiz! what’s the matter with the river?”

Larry, who was holding the target staff, grinned.

“I don’t know; I’ll ask it if you want me to,” he joked. “What do you think you see?”

“I don’t think—I know,” Dick came back. “That rock I was sighting at a minute ago was out of water. Now it’s gone under.”

“Bugs!” scoffed Larry. “You’re seeing things. There’s something the matter with your eyes.”