One by one, far down the grade, little puffs of smoke began to curl at the places where the drillers’ gangs had been working. The men, howling in mock terror, came tearing past the place where Loring and McKay were standing. They would run several hundred yards further than safety required in order to delay by a few moments their return to work when the blasting was finished. As the men surged by, McKay, in spite of his disgust, grinned. “Trust a Mex to find some way to shorten work,” he said to Loring. In rapid succession the “shots” began to go off; whole sections of the cliffs seemed to swell, then gave forth a fat volume of smoke, and finally burst, hurling fragments of brown-black rock against the sky line. Then, a fraction of an instant later, the dull, muffled boom carried to the ear. “Regular bombardment, ain’t it!” exclaimed McKay. “Wo-op! duck!” As a large jagged piece of shale came whizzing over their heads he and Loring simultaneously dropped to the ground. “Ain’t it funny?” said McKay, as they got to their feet again. “Now time and again these things won’t go fifty feet, then all of a sudden they chase a fellow who is a quarter of a mile away.” The heaviest “shot” of all was to be fired in a place near Loring’s position, where a deep spur of black diorite protruded across the grade. During five days gangs had been drilling on this spur, so that its face was honeycombed with ten deep holes, for diorite is almost as hard as iron, and to make any impression upon it requires an immense load of powder. McKay himself had superintended the loading, patting the charges firmly down with the tamping rod, until, as he expressed it, he had enough powder there to “blow hell up to heaven.” They had waited to fire these “shots” until the last of the others had exploded, and now the little group of men who were nearest began to look everywhere for shelter. The waiting teams were backed up close against the ledge, while the drivers crawled underneath the wagons for protection. Loring and McKay stood beside a large boulder, behind which they could drop when the explosion came. Into every niche men crawled, waiting for the shock. The foreman bent over the first fuse, and a wisp of thin blue smoke arose at the touch of his hand. “Hope he ain’t cut the fuses too long,” growled McKay anxiously. “If one of those loads misses fire, it won’t be safe to work in this neighborhood.” The foreman stepped quickly from fuse to fuse, and spurt after spurt of smoke began to curl from the rock, some hanging low, some rising. The foreman stooped over one of the fuses for a second time. “It’s missed!” exclaimed McKay. “No, he’s got it. Hey, _beat_ it! Quick!” he shouted, as the thin smoke began to turn from whitish-blue to yellow-brown. The foreman ran back a up the grade towards them.