Water Bells

Abstract

The author shows that when water is discharged through an annular slit above a plane water surface, the sealed ` water bells ' thus formed exhibit some novel and remarkable properties not hitherto described. The primitive water bell is a dome-shaped bubble whose dimensions increase with increased rates of flow. If this is perforated with a finger the maximum diameter of the bell suddenly doubles itself. On continuously reducing the flow the expanded bubble contracts and assumes an alternating sequence of stable and semi-stable forms of great beauty. All these, when perforated, contract slightly. The semi-stable forms have the general appearance of a hyperboloid surmounted by a saucer-shaped depression with the annular slit at the bottom. On inflating an expanded bubble by a slow stream of small air bubbles, semi-stable forms similar to the above are produced, but possessing an additional inflection in their contours. During these changes the maximum differences of pressure do not exceed one-tenth of a millimetre of water above or below atmospheric pressure. The author shows how the apparatus can easily be modified to produce enclosing water bells. It may also be adapted to produce sonic and ultrasonic underwater vibrations.