Galileo Thermometers make wonderful gifts for those interested in science and history. Galileo Galilei (1564-1642) was an important Italian scientist who founded modern physics with its reliance on experience and experiment. Among countless discoveries of natural laws, he succeeded in developing a thermometer based n the law of physics which states that the specific gravity of liquids changes as they expand at different temperatures. This principle has been used in the Galileo Thermometer. As the temperature rises, the liquid expands. Its specific gravity decreases, and the spheres sink. The current temperature is indicated by the lowest floating glass sphere in the upper part of the cylinder. The manufacturing of the Galileo Thermometer is extremely complex and done mostly by hand. The process is largely unchanged since the creation of the original Galileo thermometer more than 400 years ago. Each ball is hand-blown and calibrated to achieve an accuracy of ½ a degree Fahrenheit. They differ in weight by only two thousandths of a gram. The Liquid within is environmentally safe, biodegradable and ozone friendly.