The whole apparatus is mounted on wooden base by clips. A plant shoot is sealed into a stopper which fits the end tube and the whole apparatus is filled with water, the open end of the capillary tube, which is graduated in millimeters, dipping into beaker of water. The position of the air bubble may easily be adjusted by opening the glass stopcock to admit water from the reservoir.

The whole apparatus is mounted on wooden base by clips. A plant shoot is sealed into a stopper which fits the end tube and the whole apparatus is filled with water, the open end of the capillary tube, which is graduated in millimeters, dipping into beaker of water. The position of the air bubble may easily be adjusted by opening the glass stopcock to admit water from the reservoir.