Today in 1962, US Patent 3063841 A was issued, an invention of Michael Edward Ash, assigned to Guinness Son & Co Ltd, for his “Method of Dispensing Liquid.” There’s no Abstract, although in the description it includes this summary:

I claim: l. A method of dispensing a beverage under pressure from apressurized system into a drinking vessel so as to ensure a fine, regular and enduring head on the beverage in said vessel which comprises the steps of providing in solution in said beverage a mixture of carbon dioxide and an oxygen-free inert gas and applying a counter-pressure to said beverage which acts to maintain the pressure of the mixed gases in solution in said beverage throughout the dispensing operation without substantial variation of the partial pressure of either of said gases and also acts to expel the beverage from said system through a delivery passage and tap to the outlet thereof.