Today in 1902, US Patent 692170 A was issued, an invention of Max Wallerstein and Hans H. Freund, for their “Apparatus for Aerating Wort and Improving the Quality of Yeast.” There’s no Abstract, but this is from the description.

Our invention relates to apparatus for aerating Wort during fermentation and improving the quality of yeast, and has for its object to provide an apparatus of this class by the use of which wort is aerated with filtered air in any desired quantity during fermentation and yeast of healthy growth and great purity is obtained.