Today in 1956, US Patent 2749930 A was issued, an invention of Sumner T. Whitnall, for his “Apparatus For Dispensing Beer.” There’s no Abstract, though it’s described this way in the application:

The invention provides a solution .to the problems of dispensing from a number of barrels or other containers sequentially and facilitating replacement or interchange of empty or partially filled containers. The desired results are achieved by a tapping rod assembly which is applied to each of the several containers, each, such assembly having dispensing and pressure and transfer connections, the latter connection leading through the upper portion of the rod, but opening through a side portion thereof. above the level of the beer in the container to which beer is being transferred from a preceding container. By delivering the transferred beer (or gas, from empty barrels) at or above the level of the beer in the receiving container, I avoid turbulence, this being an important factor which makes the device of this invention. a success where other attempts to solve these problems have failed.

As the transferred beer is applied at or above the level of the beer in the receiving container, under pressure of gas applied to another container in the series, the beer in the receiving container is expelled through the rod from the bottom of the receiving container in substantially the same way as if the pressure had been applied directly to the surface of the beer in the container from which the beer is dispensed to the faucet.