A Galileo glass thermometer. From the late 20th century.
A Galileo thermometer is a decorative indoor thermometer consisting of a sealed glass cylinder filled with a clear liquid and several floating glass spheres.
It operates based on the physical principles of density and buoyancy: as the ambient temperature changes, the density of the liquid changes, causing the spheres to either sink or float.
How to read the temperature:
Each glass sphere has a precise weight and a small metal tag indicating a specific temperature (often in 2°C increments). The lowest sphere in the upper group of floating spheres indicates the current temperature. If a sphere is positioned in the middle of the cylinder—neither floating at the top nor sunk to the bottom—it is the one that indicates the temperature.
Available at the link below
https://www.tradera.com/item/741547268
