The Thermoscope or Thermomètre of Galileo is a tool of measurement of the Température, based on the principle of the Poussée of Archimedes and the Dilatation of the matter.

Physical principle

Graduated floating objects evolve/move in a liquid, in a closed circle. They are of Densité S appreciably close, and when the temperature increases, the liquid dilates, causing its fall of density. The objects lighter than the preceding density but heavier than the current one fall; and conversely when the temperature decreases.

Indication of the temperature on the image of right-hand side:

• the temperature lies between that indicated by the yellow object and that indicated by the maroon object.

Nowadays

The existing thermoscopes thus have a precision of a few milligrams for the floating objects (approximately 0,5°C). There are some to five, seven and eight balls mainly. The disadvantage is that one cannot go at too low or too high temperatures. As for all the thermometers, the exposure to the sun distorts the results. Today, they are also used as decorative objects.

See too

• Thermometer

External bonds

• Galilean Thermometer

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