This fire originated from a camp-fire which a hunting-party had left burning; it lived three weeks and extended eastward from the starting-place. Along most of its course it burned to the timber-line on the left, while rocky ridges, glacier meadows, and rock fields stopped its extension and determined the side line on the right; it ran out of the forest and stopped in the grassy Grand River Valley. Across its course were a number of rocky ridges and grassy gorges where the fire could have been easily stopped by removing the scattered trees,--by burning the frail bridges that enabled the fire to travel from one dense forest to abundant fuel beyond. In a city it is common to smother a fire with water or acid, but with a forest fire usually it is best to break its inflammable line of communication by removing from before it a width of fibrous material. The axe, rake, hoe, and shovel are the usual fire-fighting tools. A few yards away from the spot where the fire started I found, freshly cut in the bark of an aspen, the inscription:-- J S M YALE 18 A bullet had obliterated the two right-hand figures. For days I wandered over the mountains, going from fire to smoke and studying burns new and old. One comparatively level tract had been fireswept in 1791. On this the soil was good. Lodge-pole pine had promptly restocked the burn, but these trees were now being smothered out by a promising growth of Engelmann spruce. Fifty-seven years before my visit a fire had burned over about four thousand acres and was brought to a stand by a lake, a rocky ridge, and a wide fire-line that a snowslide had cleared through the woods. The surface of the burn was coarse, disintegrated granite and sloped toward the west, where it was exposed to prevailing high westerly winds. A few kinnikinnick rugs apparently were the only green things upon the surface, and only a close examination revealed a few stunted trees starting. It was almost barren. Erosion was still active; there were no roots to bind the finer particles together or to anchor them in place. One of the most striking features of the entire burn was that the trees killed by the fire fifty-seven years ago were standing where they died. They had excellent root-anchorage in the shattered surface, and many of them probably would remain erect for years. The fire that killed them had been a hot one, and it had burned away most of the limbs, and had so thoroughly boiled the pitch through the exterior of the trunk that the wood was in an excellent state of preservation. [Illustration: A YELLOW PINE, FORTY-SEVEN YEARS AFTER IT HAD BEEN KILLED BY FIRE]