  We consider a classical overdamped Brownian particle moving in a symmetric
periodic potential. We show that a net particle flow can be produced by
adiabatically changing two external periodic potentials with a spatial and a
temporal phase difference. The classical pumped current is found to be
independent of the friction and to vanish both in the limit of low and high
temperature. Below a critical temperature, adiabatic pumping appears to be more
efficient than transport due to a constant external force.
