We present a simple laboratory experiment to illustrate some aspects of the
soliton theory in discrete lattices with a system that models the dynamics
of dislocations in a crystal or the properties of adsorbed atomic layers.
The apparatus not only shows the role of the Peierls-Nabarro potential but
also illustrates the hierarchy of depinning transitions and the importance
of the collective motion in mass transport. (C) 2000 American Association o
f Physics Teachers.