be discerned as early as the notes for The Large Glass and the Bicycle Wheel readymade, and despite losing interest in “retinal art”, he retained interest in visual phenomena.
In 1920, with help from Man Ray, Duchamp built a motorized sculpture, Rotative plaques verre, optique de prcision (“Rotary Glass Plates, Precision Optics”). The piece, which he did not consider to be art, involved a motor to spin pieces of rectangular glass on which were painted segments of a circle. When the apparatus spins, an optical illusion occurs, in which the segments appear to be closed concentric circles. (Animation of Rotary Glass Plates)
Man Ray set up equipment to photograph the initial experiment, but when they turned the machine on for the second time, a belt broke, and caught a piece of the glass, which after glancing off Man Ray’s head, shattered into bits.