"The sliver-bridges, level on top at first and perfectly safe, are at length melted to thin, vertical, knife-edged blades, the upper portion being most exposed to the weather; and since the exposure is greatest in the middle. they at length curve downward like the cables of suspension bridges. This one was evidently very old, for it had been weathered and wasted until it was the most dangerous and inaccessible that ever lay in my way. The width of the crevasse was here about fifty feet, and the sliver crossing diagonally was about seventy feet long; its thin knife-edge near the middle was depressed twenty-five or thirty feet below the level of the glacier, and the up-curving ends were attached to the sides eight or ten feet below the brink. Getting down the nearly vertical wall to the end of the sliver and up the other side were the main difficulties, and they seemed all but insurmountable. Of the many perils encountered in my years of wandering on mountains and glaciers none seemed so plain and stern and merciless as this. And it was presented when we were wet to the skin and hungry, the sky dark with quick driving snow, and the night near. But we were forced to face it. It was a tremendous necessity."