The G.W. Schleidt Galileo Thermometer was originally invented 400 years ago by Galileo Galilei, a pioneer of modern physics and astronomy. The clear glass cylinder contains spheres with numerical tags suspended in a special liquid. Spheres of different weights rise or fall according to the temperature of the liquid. The lowest floating sphere in the upper part of the cylinder reveals the current temperature. This 18-inch thermometer with multi-colored floating spheres registers temperatures from 60 to 84 degrees Fahrenheit.