To demonstrate Bernoulli's principle that when a liquid flows through a tube having a constriction the speed of the flow increases and the pressure decreases in the constricted section. Consists of a horizontal tube 18 cm long and 18 mm in diameter having three vertical tubes. The tube decreases in diameter in the center to form a constriction. Made from Borosilicate Glass. Clear tubing with fluid can easily be attached and pressure differences measured.