Today in 1860, US Patent 28799 A was issued, an invention of Louis Wilhelm, for his “Ventilation of Casks Containing Liquids” or “Cock.” There’s no Abstract, though it’s described this way in the application:

The nature of my invention consist-s in the arrangement of a ventilator in the top of the cask and the connection of the same by means of a cord or chain to the tap or faucet so that when the plug of the faucet is turned to allow the liquor to escape from the cask the ventilator will be opened and admit air in at the top of the cask and when the plug is turned to stop the flow of the liquor the ventilator will close itself by the action of a spring.