Siphon barometers should not be confused with a siphon rain gauge. The siphon tube connects to the drain. A mussel draws water in through its incurrent siphon. Sea squirts feed by taking in water through a tube, the oral siphon. Their size requires control via valves at the intake, outlet and crest of the siphon. A plain tube can be used as a siphon. Apply Bernoulli's equation to point C where the siphon empties. The wastewater exits through the excurrent siphon. See aspirator and pressure head for discussion of this type of siphon. Buried bivalves feed by extending a siphon to the surface. Furthermore, this definition encompasses pumps with no moving parts, such as a siphon. The apparatus will then continue to operate as a normal siphon. Such a design includes the volute siphon. Another possibility is that it comprised two jars, connected by a siphon. The airstream creates a Bernoulli or siphon.