It was an invention of Philon of Byzantium which always kept a goblet of wine full, regardless of the quantity removed.
It consisted of an air-tight vessel full of wine with a horizontal tube-tap that led to a goblet. The perforated bottom of the goblet led to a hollow base (horizontal piping with a vertical tube that reached the height of the goblet). A smaller tube that started from the top of the air-tight vessel penetrated its bottom and entered the vertical tube of the hollow base in a depth equivalent to the desired level of the wine in the goblet. The level of the wine in the vertical tube of the hollow base fell after the removal of a certain quantity of wine from the goblet, thus, allowing the entrance of air through the smaller tube in the air-tight vessel. This led to the flow of wine towards the goblet and to the increase of its level in the hollow base. When the level of the wine reached the mouth of the smaller tube of the vessel it created vacuum and the flow stopped.