A ring stands, with axis horizontal, on a horizontal table and a cylinder is placed, also with axis horizontal, resting within it. If motion in thesamehorizontal direction be given to both, they both roll and the motion is of no particular interest. If, however, motion inoppositedirections be given to the ring and the cylinder “rocking” occurs. This motion is interesting because its theoretical solution involves the use of Lagrangian equations, there being two degrees of freedom. Theory and experiment are here given for rings (thin and thick, complete and semicircular) and cylinders (hollow and solid) of different sizes. Good agreement is observed.