How do siphons work? Some see atmospheric pressure, explicitly or implicitly, as a crucial factor in siphon action. Others explain that a siphon works due to a difference of water weights in unequal arms. According to the latter view, siphon action is analogous to the action of a pulley or to the behaviour of a chain that is moving over a tube. In this article, we show that a siphon made from non-uniform tubing disproves the validity of the pulley analogy. Our pedagogical experiments were inspired by the critique that Hero formulated many years ago. (Contains 7 figures.)