Today in 1911, US Patent 1001805 A was issued, an invention of Chris Bergsvik, for his “Beer-Preserver.” There’s no Abstract, although in the description it includes this summary:

My invention relates to beer preservers or beer-pressure apparatus. Its object is to provide a device which shall constantly maintain the pressure during the dispensing of the beer and thus preserve the constant gaseous pressure necessary to keep the beer from staling.