Today in 1904, US Patent 770271 A was issued, an invention of John M. Doehrer, for his “Liquid-Drawing Apparatus.” There’s no Abstract, although in the description it includes this summary:

The object of my invention is to draw beer or other like liquids from the top or bottom of the keg and automatically seal the outlet or bung when the draft-pipe is withdrawn to apply an air-pressure on the top of the beer to force it up through the draft-pipe when drawing the beer.