Today in 1986, US Patent 4610888 A was issued, an invention of James Teng and John H. Dokos, assigned to the Anheuser-Busch Companies, Inc., for their "Beer Foam Enhancing Process and Apparatus." Here's the Abstract: A beer foaming process and apparatus in which a smooth stable foam is formed by intimately admixing a nitrogen containing gas, preferably air, by a Venturi effect in a nozzle positioned on the beer tap.