1. pump, sprengel A form of mercurial air pump. A simple form is shown in the cut. Mercury is caused to flow from the funnel A, through c d to a vessel B. A side connection x leads to the vessel R to be exhausted. As the mercury passes x it breaks into short columns, and carries air down between them, in this way exhausting the vessel R. In practice it is more complicated. It is said to give a better vacuum than the Sprengel pump, but to be slower in action.