Multi-Colored Glass Galileo Thermometers

Galileo discovered centuries ago that a liquid's density varies with temperature.
These works of scientific art contain colored glass temperature indicator spheres calibrated to within a fraction of a gram to measure indoor temperature accurately.


The balls float in a clear liquid, changing position with fluctuations in temperature. The lowest floating sphere indicates the current temperature. We offer four different models, ranging in size from 11" to an impressive 24".

• 11" : 64-80 F in 4 degree increments
• 14" : 62-86 F in 4 degree increments
• 17" : 66-84 F in 2 degree increments
• 24" : 62-82 F in 2 degree increments

The Galilean thermometer works due to the principle of buoyancy, a force exerted by a fluid that opposes an object's weight. As the temperature of the air outside the thermometer changes, the temperature of the water surrounding the bubbles also changes. When the temperature of the water changes, it either expands or contracts, changing its density. Each bubble also differs slightly in density from the other bubbles. The bubble that sinks the most indicates the approximate current temperature. Named for “The father of modern observational astronomy,” Galileo Galilei, an Italian physicist and astronomer responsible for many astronomical advancements.