The instrument is supported by a wooden tripod frame holding a plate that serves as base for a bell-jar. A faucet connects the plate to an upright iron tube. The latter communicates with an upright wooden tube attached to the frame as well. A wooden rod fitted with a handle runs up and down inside the barrel. There is a box at the base of the barrel, which originally contained a valve. The pump was restored after being damaged in the 1966 Arno flood, and because of the many missing parts its exact mechanism cannot be determined. However, this type of mercury pump resembles the one described by Emanuel Swedenborg in his Miscellanea of 1722. The vacuum was obtained by lowering and raising the mercury column in the upright tube by the pumping action of the wooden rod. Resembles item inv. 1531. Provenance: Lorraine collections.