The book excerpt below mentions two ways of controlling the descent of a horse-drawn wagon on a steep mountain road: Locking a wagon wheel with a lock chain, and dragging a log or tree top behind the wagon.
+++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++