Galileo Thermometer

I have a little row of these on my window cill -differing heights. some in degrees F and some C! On the basis of the instructions below, it was a warm day!

"These bright and attractive thermometers were first envisioned by Galileo Galilei (1564 – 1642) in his search for an exact temperature measurement.
 
How it works: In liquid, each globe with the same weight and size is compelled to go down as the temperature rises. The globe will rise if the temperature falls. The lowest suspended globe in the upper part of the cylinder equals the right temperature."