This instrument is a glass tube with a conical brass valve and a brass circular base.
Piezometers are instruments used in studying the compressibility of solids and liquids.
The Oersted Piezometer was used to determine the coefficient of the compressibility of liquids. Gases would have been pumped into the chamber through the funnel at the top. The pressure of the gases would have been measured via the water barometer inside the main glass tube.
For more information:
Identifier: MP 275.0