Today in 1877, US Patent 195980 A was issued, an invention of George J. Cave and George E. Nicholson, for their “Improvement in Gage Attachments for Beer-Measures.” There’s no Abstract, although in the description it includes this summary:

The object of this invention is to furnish an improved measure for measuring beer and other liquids that foam when drawn, which shall be so constructed as to show at once how much of the liquid there may be in the measure, however foamy it may be, so that there need be no waiting for the foam to subside, and no refilling.

The invention consists in the combination of the detachable glass tube, the rubber rings, and the screw-plug with the case,the measure, and the elbow-pipe connected with the interior of the measure, or with a box or trap secured within said measure; and in the combination of the screw-cap, provided with the hole and the handle, with the box or trap secured in the interior of the measure, and connected with a glass tube by an elbow-pipe, as hereinafter fully described.