Measurements have been made of two dimensional motion of an elastically supported circular cylinder in the wake of a fixed upstream cylinder. The experiments were made in a water flow channel with diameter cylinders with a maximum Reynolds number of 77,000. The elastically supported downstream cylinder moves downward and inward toward the centerline of the upstream cylinder’s wake with increasing flow velocity, indicating the presence of a transverse lift force and reduced drag in the wake. These forces can cause the cylinders to clash. The measured motions correlate with the theory.