Glass Galileo thermometer / temperature gauge

Galileo thermometer based on an idea by Galileo Galilei (1564-1642).

He discovered that the density of a liquid changes as temperature varies. Each of the glass bulbs is exactly weighted by being partially filled with liquid. When the temperature rises, the liquid in the glass cylinder becomes less dense, and the heavier bulbs sink slowly to the bottom.

The temperature is read from an engraved metal disc on each bulb (19, 21, 23 and 25 degrees Celsius). Depending on the temperature, a gap separates the top group of bulbs from the bottom group of bulbs, meaning the temperature would be between the tag readings on either side of the gap. If a bulb is free-floating in the gap, then its tag reading would be closest to the ambient temperature.

The thermometer measures 29cm high.


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