The mechanics of cinema are based on the division of the film into frames, projected one after another at a fixed rate of 24 frames per second, giving an illusion of continuity. Richard Serra’s film, Hand Catching Lead, illustrates the mechanism. Echoing the vertical movement of the film through the projector, pieces of sheet lead fall into the image field. Serra’s hand opens and closes as it tries to catch them, and when it succeeds, immediately lets them go again, reproducing the intermittent advance of the film. But that is not all, for as the action progresses, Serra’s hand, blackened by the lead, shadow-like comes to resemble the silhouette of a dog trying to catch something thrown to it, thus referring the mechanics of cinema back to its origins in the art of shadow theatre.