Today in 1885, US Patent 325316 A was issued, an invention of Edward A. Byrne, for his “Beer-Faucet.” There’s no Abstract, although in the description it includes this summary:

Our invention comprises a novel construed of those faucets having air-inlets, and which are employed more especially for drawing off beer, ale, and other liquors from kegs and similar receptacles. Heretofore it has been customary to pass the air tube or inlet through the heel of the faucet and carry the almost to the top of the keg, so as to allow the air to act directly on the surface of the liquor, and thereby afford the proper ventage the instant the faucet is opened. Practical experience, however, has demonstrated that this is a very defective arrangement, inasmuch as the introduction of the air within the keg causes the beer or other liquor to become sour unless it is drawn off quite rapidly; hence such faucets are not adapted for use in small saloons, the proprietors of which places of resort demand a faucet that will afford the necessary ventage, and yet will not canse their liquors to become dat and unsalable. To meet these requirements we have devised a faucet the heel of which has one or more lateral ports, while the inner end of said heel is closed, so as to prevent the liquor taking a direct central passage through the axial channel. Furthermore, the discharging end of the tube or inlet is located in the rear of these ports in order that the flow of beer through the latter will cause a current of air to traverse said inlet and mingle With the liquor as it escapes from the faucet. By this arrangement the proper ventage is afforded, while at the same time there is no possibility of the air entering the keg or barrel, it being understood that the construction of the device is such as to allow the inlet to be opened only when the faucet-plug is so turned as to draw of the liquor