This Galileo Thermometer stands at 18cm tall. A beautiful thermometer with multi coloured temperature reading balls. Contains 4 internal temperature reading globes with temperature reading Tags which are gold coloured & read temperatures between 20-26C. History of the Galileo The physicist Galilio Galilei (1564-1642) discovered that density of liquid changes according to temperature. This principle is used within the Galileo Thermometer, Depending on the temperature, the glass bulbs in the thermometer either rise or fall. The actual temperature is shown by the lowest of the upper floating glass coloured bulbs. These Galileo's are finest top quality & not to be confused with cheaper imitations. Made from blown glass in Germany they really do make a perfect gift that will be admired- certainly not another dust collector.