Fa-7 Cartesian Diver


To demonstrate the workings of a Cartesian Diver.


  • Perspex Cylinder
  • Rubber Diaphragm
  • Pipette Tube
  • Eye Dropper
  • Water
  • Hose Clamp

Cartesian Diver 1 Cartesian Diver 2

Cartesian Diver


The Cartesian Diver consists of pipette like structure with an eye dropper mounted on the top of it. With the eye dropper off, the cartesian diver is immersed into a cylinder to a predetermined level, then the eye dropper is mounted on top. The cartesian diver should just float. It may be necessary to repeat the process by adjusting the water level within the cartesian diver if it doesn’t float. Then place the rubber diaphragm tightly over the top of the cylinder and secure with hose clamp.  Pressing down on the rubber diaphragm will see the Cartesian Diver sink. Release the pressure on the rubber diaphragm and the cartesian will float again. Pressing down on the rubber diaphragm increases the air pressure above the water level, which in turn increases the water pressure. This causes the water level within the cartesian diver rise causing the cartesian to weight to increase, subsequently causing the Cartesian Diver to sink. Releasing the pressure of the rubber diaphragm reduces the air pressure above the water, thus reducing the water pressure. Subsequently the water level in the Cartesian Diver will fall, reducing the weight. The Cartesian diver will float again. It also must be noted that air inside the Cartesian Diver is compressed when the pressure is applied to the rubber diaphragm. Causing the air to become denser.