Today in 1892, US Patent 486485 A was issued, an invention of Joseph Lehr and Joseph Bodani, for their “Pressure Regulator.” There’s no Abstract, although in the description it includes these claims:

Our present invention has for its objects to provide a device adapted to maintain an even pressure of air, gas, or other fluid in a chamber or receptacle supplied from a suitable source, which pressure is capable of easy regulation, and though it is especially adapted for maintaining an even and regular pressure on the beer in a keg from which it is being drawn said device is obviously capable of use in other connections and for other purposes; and to these ends it consists in certain improvements in construction and combinations of parts, all as will be hereinafter fully described, and the novel features pointed out particularly in the claims at the end of this specification.