In late 1965 Rickey extended his vocabulary from lines to planes to create enchanting and evocative drawings in space that would further focus on the motion of the work. Two Planes Vertical-Horizontal II is a visually simple, engaging work that takes the moving square as its subject. Two internally weighted shallow boxes made of burnished stainless steel pivot on either side of a similarly burnished round pole, to which they are attached. Like Rickey’s Six Lines in a T, the Planes are compound pendulums—objects with weights above and below the pivot point—that move in parallel paths. A small trap door allows for access to the internal ball bearings and supporting structure, counterweights for the compound-pendulum system. Styrofoam filling ensures the boxes move without making a sound.