Click for animation.

Brighten up your demonstrations with this blown glass Cartesian diver.

Click on the image to the left to see a pop-up animation of the diver. Our set-up was as follows:

• Small acrylic selzer bottle - rinsed without label
• Snap tail (lower right image) off diver near to the tail's base.
• Fill bottle and float diver upright
• Screw cap tightly on bottle

Squeeze the bottle and the diver sinks. Let go and it surfaces.

When the bottle is squeezed, the air compresses as water is nearly incompressible. The air bubble in the diver shrinks allowing more water flow inside and increasing the density of the diver. By Archimedes' principle the buoyant force on the diver remains constant, so the diver falls to the bottom. When you let go, the process is reversed.

The paint on individual divers may vary.

Dimensions: diver is about 3" (7.6 cm) in height.

Click to enlarge.