Today in 1909, US Patent 928588 A was issued, an invention of Harry S. Cornish, for his “Apparatus for Dispensing a Measured Quantity of Beer.” There’s no Abstract, although in the description it includes this summary:

My invention is primarily designed for dispensing beer and to regulate what is known as the pint trade.

The main object of my invention is to avoid any waste of liquid when changing from one source of supply to another and to insure that the first liquid drawn from the new source will be of the full measured quantity.

To these ends my invention consists in providing an apparatus for drawing a measured quantity of liquid with means for changing from one source of supply to another, when the first has become exhausted, together with means for venting or freeing the air from the pipes and intermediate connections of the empty end of the system previous to connecting the new supply, so that the new supply can immediately fill the empty end and a full measured quantity drawn at the first draft from the new supply.