Siphons, Revisited Available to Purchase

The siphon is a very useful example of early technology, the operation of which has long been well understood. A recent article¹ makes the claim that established beliefs regarding this device are incorrect and proposes a “chain model” in which intermolecular forces within the fluid play a large role while atmospheric pressure does not. We have carefully tested, and disproved, this claim using four simple experiments employing inexpensive, easily available apparatus. We complement the experiments with a discussion of conceptual issues related to the device and by invoking earlier studies and observations.^2–8 Our findings fully support an explanation based on Bernoulli's equation in which both gravity and pressure play important roles, but intermolecular forces do not.