Today in 1879, US Patent 222639 A was issued, an invention of James A. O’Connor, for his “Improvement in Apparatus for Forcing Beer from Casks.” There’s no Abstract, although in the description it includes this summary:

My invention relates to an improved apparatus for maintaining the pressure in beer-4 casks, and for preserving the freshness of the beer While it is being drawn from the casks and it consists in the combination, with an air-pump, of an air-reservoir connected to the beer-cask by a suitable pipe, the said reservoir-being composed of two cylindrical or polygonal vessels, closed at their outer ends, and arranged to slide one within the other through a packed joint, as hereinafter more fully described.

And here’s the original drawing filed with the application: