What is a Galileo thermometer and how does it work? Galileo Galilei (1564 - 1642) was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His findings provided the framework for Newton's laws of motion and Einstein's theory of relativity. His discovery that the density and volume of a liquid changes in proportion to its temperature, inspired the invention and explains the accuracy of this thermometer. These unusual thermometers contain colorful orbs which rise and fall to indicate the current temperature. Made of high quality glass, these thermometers are individually calibrated to achieve an accuracy of 2°F. Under normal conditions, the orbs will settle into two groupings toward the top and bottom of the glass column. To read the Galileo Thermometer, observe the golden tags hanging from each orb. The golden tag on the lowest orb in the top grouping displays the current ambient temperature.