Men working with chisels had cut out of the steep cliff a running rectangle of rock to make this path. It was scooped out of the flat face of the mountain, which was too perpendicular to permit an ordinary ledge being formed. The path had a ceiling, an inner wall, and a floor of solid rock; all it had for outer wall was peril. It ran more or less, but not exactly, on a horizontal plane; wherever possible, it followed strata of rock, presumably along the softer faults in the limestone.

I can still see vividly in my mind’s eye Old Pebble entering that dangerous place.

I remember that in the gorge itself, that day, the sight gave me a sickening feeling, and now, these many years later, the memory of it still faintly does.

The cliff was sheer, rising at an angle, I would say, of more than eighty degrees; I have a distinct impression that in some places in Wind-Box Gorge parts of the mighty precipices actually overhang the river. Where it began, the path was about thirty feet above the surface of the water, so that from the deck of the junk we looked up at it, more than half the height of our mast. Su-ling told me that in winter, at low water, at what the rivermen call “zero,” the path would be more than sixty feet above the surface, while late in the spring, perhaps a month after we were there, it would be nearly as much, or more, under the surface. When the melted snows of many mountains of Tibet course toward the sea, and when, riding the crests of those thaws, the run-off of spring rains that have fallen on half a million square miles of Chinese hills flow too down the Great River, its power becomes unimaginable, even to a hopeful young hydraulic engineer.

These were the very cliffs against which, in its record year, the river had climbed in a short time two hundred and seventy-five feet.