Today in 1941, US Patent 2229875 A was issued, an invention of Robert Schwarz and Fred L.A. Schmidt, for their “Art of Wort Cooling.” There’s no Abstract, but here’s the general idea.

Generally speaking, the invention involves cooling the wort by evaporation in a cycle which includes the passage of clean, filtered air or air 2o rendered germ-free by other methods, along or across the path of a flat expanded stream in which the wort is introduced into a closed chamber. Where the cooling after such operation is inadequate, the wort or some of it is pumped in go one or more repetitions of said cycle until the desired cooling has been effected.