Using their hands for the most part, or a thick bough, the trappers swept the deep snow which lay on the rocky ridge into a wall some three feet high, and now that that portion directly in front of the hollow was completed, they pushed on with the work to the right of the fort, where the hummock or rock ran on without interruption, presenting a ledge some ten feet wide, which was perfectly level. To the left the rock fell away suddenly just outside the hollow, and it would have been impossible to erect even a narrow wall. "Reckon that air a good idea of yours, Cap'n," said Pete, as he beat the snow with his hands to make it bind firmly together. "When them critters gets out'er the trees and makes for the hollow, the snow'll puzzle 'em a little, and they won't be properly sure whereabouts the mouth of the hollow lies. Chances air that not a one of 'em's ever set foot in it. They've likely enough looked up here a score of times jest in the ordinary way of scoutin'. But that won't help 'em much, particular when the hul place is changed by the snow." "Just what I thought," answered Steve. "If we were to open fire from behind the wall erected just in front of the hollow, the smoke would give our position away to them at once, and they would soon send their cannon balls plumping into the place. As it is, we can crawl away behind the wall till we are well to the right, and there----" "Reckon cannon balls don't do much harm against rock, Cap'n," burst in Jim. "The only thing now is to be careful that them critters don't see us at work as they come out of the trees. Best call some of 'em in."