Inverted siphon, a tube bent like a siphon, but having the branches turned upward; specifically (Hydraulic Engineering), a pipe for conducting water beneath a depressed place, as from one hill to another across an intervening valley, following the depression of the ground. -- Siphon barometer. See under Barometer. -- Siphon bottle, a bottle for holding aërated water, which is driven out through a bent tube in the neck by the gas within the bottle when a valve in the tube is opened; -- called also gazogene, and siphoid. -- Siphon condenser, a condenser for a steam engine, in which the vacuum is maintained by the downward flow of water through a vertical pipe of great height. -- Siphon cup, a cup with a siphon attached for carrying off any liquid in it; specifically (Mach.), an oil cup in which oil is carried over the edge of a tube in a cotton wick, and so reaches the surface to be lubricated. -- Siphon gauge. See under Gauge. -- Siphon pump, a jet pump. See under Jet, n.