Today in 1937, US Patent 2083340 A was issued, an invention of Herman Merker, assigned to the Pressed Steel Tank Company, for his “Metal Barrel.” There’s no Abstract, although in the description it’s explained as follows:

This invention relates to a metal barrel particularly designed and adapted for use as a beer barrel or as a container for similar beverages although also well adapted for other uses. One object of the invention is to provide a barrel with a strong and durable bung structure, one which will stand up under the severe usage to which such a structure is subjected and yet preclude fatigue or distortion of the metal adjacent the bung structure. Another object of the invention is to provide a barrel having a bung structure of the character mentioned and one which does not interfere with easy rolling and handling of the barrel.