Add some color and fun to your lessons on specific gravity with a colorful and dramatic Galileo thermometer. Galileo Galilei (1564-1642) succeeded in developing a thermometer based upon the law of physics which states that the specific gravity of liquids changes as they expand at different temperatures. Add multicolored liquids in sealed bulbs in a large sealed tube and you have a captivating permanent demonstration of this important principle. Each bulb in the thermometer is partially filled with a different colored fluid and a metal tag beneath it with a printed Fahrenheit temperature. The bulbs are in continual motion up and down the column as the temperature changes. The current actual temperature is indicated by the lowest floating sphere in the upper part of the cylinder. Two sizes are available.