Intermittent motion of a camphene disk at the center of a cell

The self-motion of camphene on water was investigated as a simple example of an autonomous motor. When a camphene disk was floated on water in a small Petri dish as an isotropic system, intermittent motion (alternating between rapid motion and rest) was observed at the center of the Petri dish. The floating state of the camphene disk changed periodically in association with the intermittent motion. When a camphene disk connected to a plastic boat as an anisotropic system was floated on water, uniform motion was observed. The nature of this self-motion is discussed in relation to the floating state of the camphene disk depending on convection and the surface tension of the camphene layer as the driving force.