《水经注·卷一》
从前有人在崖壁上凿石开路，架设了竖梯。一共要爬七百道梯子方才爬完，然后踩着索桥过河。沿河两岸相距都有八十来步。
昔人有凿石通路施倚梯者，凡度七百梯，度已，蹑悬絙过河，河两岸，相去咸八十步。
In the past, someone carved out a path on the cliff and set up vertical ladders. One had to climb a total of seven hundred ladders before crossing the river on a rope bridge. The distance between the two banks of the river was around eighty paces.