In the cellar that strange upside-down bottle

The cellar’s glass airlock has a lower section communicating with the wine and an upper water-filled section closed by an inverted-glass-shaped cap. Inserted into a tank opening or cask bunghole, it allows topping-up without opening the vessel. Its transparency reveals whether the wine level is rising or falling, while its bubbling function lets gas or liquid escape without allowing air to enter. The article attributes this type of crystal airlock to Monsignor Arcangeli in the nineteenth century, while noting that an association with Leonardo da Vinci lacks documentary support.