Galileo Galilei, the pioneer of modern physics and astronomy, never could have imagined that the remarkable thermometer he invented four centuries ago, would become one of the most attractive, intriguing and eyecatching gift items today. The Galileo Thermometer is a glass cylinder filled with colorful spheres that measure the correct temperature based on a fascinating scientific principle. What Galileo discovered is that spheres of different weights would rise or fall according to the temperature. Because the liquid in the cylinder contracts slightly at lower temperatures and expands at higher temperatures, the spheres rise and fall accordingly. In a Galileo Thermometer, the lowest floating sphere in the upper part of the cylinder tells the correct temperature within 2 degrees. Galileo Thermometer with Barometer (Fill the barometer with liquid to gauge the current barometric pressure.)