Tantalus Cup 

• A Tantalus cup is a  glass  cup  with  a  U-tube  attached.  When  water  reaches  the  top  of  the 
        inverted U-tube, a siphon action begins which drains the water until the end of the U-tube is 
        exposed.
• When the cup is filled with water, the water is forced up the inverted U-tube so that equilibrium 
        is maintained in the cup.
• As the water level reaches the top of the U-tube it begins to fall through the siphon. As the water 
        falls, it creates a vacuum which causes more water to be forced into the tube.

*Note: image shown above is for illustration purpose only; Actual image may vary due to specification, Design, Technology and R&D.*