By noon they were ready to fire another round of blasts in the tunnel, and they did it, retreating as before into the depths of the cave, in the confident assurance that the sputtering fuses would be a sufficient protection against an invasion for the few minutes they would have to leave the cave mouth unguarded. The roar of the blasts followed quickly, and after the gas had been given time to dissipate itself, the sorting process began again, this time with Dick doing guard duty.
“I don’t see but what we can keep this thing up indefinitely, as long as our grub lasts,” Dick said, as he took his place as sentry. “This old cave is as safe as a fort. They can’t possibly rush us, so long as we keep watch and are ready for them.”
“It’s a matter of brains,” Larry offered. “They’re a poor lot if they can’t think up something better than anything they’ve tried yet.”
The words were hardly out of his mouth before they all heard what sounded like the rumble of a distant explosion.
“What was that?” Purdick demanded, and as he spoke the answer came, first in an avalanche of earth and small stones rattling down from above upon their “dooryard” ledge, and an instant later in the thunderous fall of a huge boulder that, striking fairly upon the ledge, bit a huge scallop out of it exactly in front of the cave entrance as it went grinding and crashing on into the gulch, mowing down big trees in its path as if they were dry weed stalks.
At the first rattling warning, Dick had thrown himself back into the crevice, and it was well that he did so, for the impact of the mighty projectile upon the ledge was like the explosion of an enormous shell, sending flying fragments of stone in all directions.
“Speaking of brains,” Dick gasped, when he could get his breath, “I guess they’ve got a few right along with ’em. Gorry! They must have shot a whole mountain down on us! Our dooryard’s gone, clear up to the hilt!”
Dick’s announcement was no exaggeration. Where there had been a step-like ledge and a straight drop from the edge of it, there was now a great gash and a steep slope running quite up to the cave mouth. And the protection which the projecting ledge had given them from rifle fire from below was gone. A good marksman in the gulch could now shoot directly into the crevice, still at a high angle, to be sure, but not so high but that the bullets could penetrate for a dozen feet or more before they would hit the roof.
While the avalanche aftermath of little stones and earth was still clattering down from the cliff brink above, the bombardment was renewed. Every few minutes, at the crack of a gun in the gulch, a whining missile would come through the exposed crevice mouth to hit the roof and scatter stone splinters and bits of hot lead all about the place.
“Well,” said Dick, after they had quickly withdrawn out of the line of fire, “what next?”